Prepared in cooperation with the

Southwest Florida Water Management District

Scientific Investigations Report 2009–5140

U.S. Department of the Interior

U.S. Geological Survey

Hydrologic Conditions that Influence 

Streamflow Losses in a Karst Region of the 

Upper Peace River, Polk County, Florida

By P.A. Metz and B.R. Lewelling
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

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Suggested citation:

Metz, P.A., and Lewelling, B.R., 2009, Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the 

Upper Peace River, Polk County, Florida: U.S. Geological Survey Scientific Investigations Report 2009-5140, 82 p.

978 1 4113 2545 6
Contents

Acknowledgments........................................................................................................................................ix

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

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

Purpose and Scope ..............................................................................................................................4

Methods of Investigation.....................................................................................................................4

Previous Investigations........................................................................................................................6

Upper Peace River Basin Characteristics.................................................................................................6

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

Hydrography ........................................................................................................................................10

Land Use...............................................................................................................................................10

Soils.......................................................................................................................................................15

Groundwater Use................................................................................................................................15

Geologic Framework ...................................................................................................................................19

Geologic Cores....................................................................................................................................21

Karst Development .............................................................................................................................23

Hydrogeology................................................................................................................................................24

Surficial Aquifer..................................................................................................................................24

Intermediate Aquifer System............................................................................................................24

Upper Floridan Aquifer.......................................................................................................................25

Potentiometric Surface.............................................................................................................29

Long-Term Trends in Groundwater Levels.............................................................................30

Streamflow....................................................................................................................................................31

River Channel Characteristics Affecting Upper Peace River Flows ..........................................31

Streamflow Conditions (2002-2007 Water Years)..................................................................35

Discharge-Duration Hydrographs and Curves .....................................................................44

Effects of Karst Development on Streamflow Losses ..................................................................49

Seepage Investigations ............................................................................................................49

Karst Features along the Upper Peace River........................................................................53

Streamflow Losses to Karst Features ....................................................................................53

Effects of Groundwater Conditions on Streamflow Losses.........................................................67

Groundwater Flow Patterns Surrounding the Upper Peace River....................................68

Flow Patterns Derived from Chemical Constituents and Isotopic Tracers ......................71

Influence of Large Karst Features on Flow Patterns and Streamflow Losses ................75

Summary and Conclusions.........................................................................................................................77

References Cited..........................................................................................................................................79

iii
Figures

1. Map showing location of the upper Peace River basin and the localized 

 study areas along the upper Peace River, Polk County, Florida...............................................3

2. Map showing physiographic subdivisions and location of sinkholes in the 

 upper Peace River basin.................................................................................................................7

3. Graphs showing annual rainfall at Bartow, Florida (1900-2007), and rainfall 

 departure, 5-year moving average of this departure, and changes in the 

 Atlantic Multidecadal Oscillation ..................................................................................................9

4. Graph showing Palmer Drought Severity Index for the study area for the 2001 to 

 2007 water years.............................................................................................................................10

5-8. Maps showing:

5. Historical hydrography (1850-1855) of the upper Peace River basin ...........................12

6. Historical (1850-1855) and current (1985) hydrography of the upper 

 Peace River basin ...................................................................................................................13

7. Land use in the upper Peace River basin, 2005 ................................................................14

8. Generalized soil types in the upper Peace River basin ...................................................16

9. Graph showing location of the Southern West-Central Florida Groundwater Basin, 

 estimated groundwater use in the Southern West-Central Florida Groundwater 

 Basin and in the upper Peace River basin, and estimated groundwater use by 

 category in the upper Peace River basin, 1992 through 2005.................................................17

10. Map showing major water-use categories and pumpage distribution for groundwater 

 withdrawn from the Upper Floridan aquifer in the upper Peace River basin, 2005 ............18

11. Graph showing relation of stratigraphic and hydrogeologic units.........................................19

12. Geologic cross-section along the upper Peace River and water levels for study 

 wells that indicate recharging conditions (June 1, 2007)........................................................20

13. Map showing location of stream gaging stations, geologic cores, sinks, and 

 groundwater monitoring and water-quality sampling sites ....................................................22

14. Photograph showing secondary porosity of the Arcadia Formation within the 

 intermediate aquifer system (Gator Sink) ..................................................................................25

15-17. Graphs showing:

15. Geophysical logs for well site LW1P.................................................................................. 26

16. Geophysical logs for well site LW3P.................................................................................. 27

17. Geophysical logs for well site LW4P.................................................................................. 28

18. Map showing predevelopment and May 2007 potentiometric-surface levels 

 and regional groundwater flow patterns of the Upper Floridan aquifer within the 

 upper Peace River basin...............................................................................................................29

19. Graph showing long-term discharge from Kissengen Spring, and long-term 

 water levels in observation wells tapping the Upper Floridan aquifer and 

 intermediate aquifer system.........................................................................................................31

20. Maps showing changes in the potentiometric surface of the Upper Floridan 

 aquifer between predevelopment and May 1975 and May 2007 levels for the 

 Southern West-Central Florida Groundwater Basin, and between predevelopment 

 and May 2007 and September 2007 levels for the Upper Peace River basin.......................32

21. Graph showing comparison of potentiometric-surface profiles of the Upper 

 Floridan aquifer for predevelopment and recent conditions ..................................................33

22. Map showing locations of stream Reaches 1-4 and discharge measurement 

 sites on the Peace River and tributaries during seepage runs ..............................................34

iv
23-29. Graphs showing:

23. Departure from the average discharge and rainfall for the 2002-2007 

 water years ............................................................................................................................. 35

24. Daily mean discharge for Reaches 1 and 2 for the 2002 water year, the 

 2002 low-flow period, and daily mean discharge for Reach 3 for the 

 partial 2002 water year......................................................................................................... 36

25. Daily mean discharge for Reaches 1 and 2 for the 2003 water year, the 

 2003 low-flow period, and daily mean discharge for Reach 3 for the 

 2003 water year...................................................................................................................... 37

26. Daily mean discharge for Reaches 1 and 2 for the 2004 water year, the 

 2004 low-flow period, and daily mean discharge for Reach 3 for the 

 2004 water year...................................................................................................................... 38

27. Daily mean discharge for Reaches 1 and 2 for the 2005 water year, a 

 high-flow period during 2005, and daily mean discharge for Reach 3 for the 

 2005 water year...................................................................................................................... 39

28. Daily mean discharge for Reaches 1 and 2 for the 2006 water year, the 

 2006 low-flow period, and daily mean discharge for Reach 3 for the 

 2006 water year...................................................................................................................... 40

29. Daily mean discharge for Reaches 1 and 2 for the 2007 water year, the 

 2007 low-flow period, and daily mean discharge for Reach 3 for the 

 2007 water year.......................................................................................................................41

30. Maps showing land-surface elevation contours along the upper Peace River at 

 88, 90, 92, and 94 feet above NGVD 1929 ....................................................................................46

31-35. Graphs showing:

31. Approximate range of water-level elevations for which the upper 

 Peace River is within the main channel ............................................................................ 47

32. Daily flow-duration hydrographs for Peace River at Bartow, water years 

 1940 through 2007.................................................................................................................. 47

33. Discharge-duration curves for the Peace River at Bartow, Peace River 

 near Bartow, and Peace River at Clear Springs gaging stations for the 

 2002, 2003, 2004, 2005, 2006, and 2007 water years, with a long-term 

 comparative curve for the Peace River at Bartow gaging station for the 

 1940-2007 water years.......................................................................................................... 48

34. Comparison of flow losses and gains for seepage runs conducted during 

 May 1996, May 2003, January 2006, and June 2006 from the Peace River 

 at Bartow to the Peace River at Fort Meade gaging stations ...................................... 50

35. Streamflow losses along Reaches 1 and 2 from the Peace River at 

 Wabash to the Peace River at Clear Springs gaging stations ...................................... 51

36. Map showing location of karst features in Reaches 1 and 2 ..................................................54

37-39. Photographs showing:

37. Examples of karst features along the upper Peace River.............................................. 56

38. Karst features in Reach 1 along the upper Peace River................................................. 58

39. Karst features in Reach 2 along the upper Peace River................................................. 59

40. Maps showing elevation of sinks and riverbed channel along the lower end 

 of Reach 2, and detailed view of Dover Sink .............................................................................64

41. Photographs showing changing hydrologic conditions at Dover Sink..................................65

Figures (Continued)

v
42. Graph showing topographical profile of Peace River channel and Dover Sink 

 Distributary......................................................................................................................................66

43. Photograph of inflow to Dover Sink Distributary from two sources—from Peace 

 River flowing south and Sixmile Creek flowing north—and graph showing 

 comparison of discharge from Peace River at Clear Springs and Sixmile Creek ...............66

44-49. Graphs showing:

44. Relation of streamflow losses to aquifer water levels in Reaches 1 and 2 

 during seepage measurements........................................................................................... 67

45. Long-term hydrograph for ROMP 59 Avon Park Upper Floridan aquifer 

 well and hydrographs for the study period for Upper Floridan aquifer wells 

 at LW1P, LW3P, and LW4P monitor sites........................................................................... 69

46. Comparison of the Peace River stage and water levels in monitor wells 

 completed at different depths in the intermediate aquifer system and 

 Upper Floridan aquifer.......................................................................................................... 70

47. Stiff diagrams for surface-water and groundwater sites along the upper 

 Peace River............................................................................................................................. 72

48. Delta deuterium in relation to delta oxygen-18 in Peace River surface water 

 and groundwater at selected well sites and the percentage of river water in 

 groundwater using delta oxygen-18 .................................................................................. 75

49. Comparison of water levels in wells and sinks within the upper Peace River 

 karst area................................................................................................................................. 76

Tables

1. Streamflow statistics for the upper Peace River and tributaries for the 2002-2007 

 water years ......................................................................................................................................42-43

2. Computed and measured discharge at selected sites and total streamflow losses 

 along Reaches 1 and 2 during below-average flow conditions....................................................52

3. Location and description of major karst features along the upper Peace River........................55

4. Discharge measurements of streamflow losses to karst features in Reaches 1 and 2 

 along the upper Peace River...............................................................................................................57

5. Characteristics and data summary for wells and sinks located along the upper 

 Peace River............................................................................................................................................69

Figures (Continued)

vi
vii

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre (ac) 4,047 square meter (m2

)

acre (ac) 0.4047 hectare (ha)

square foot (ft2

) 0.09290 square meter (m2)

square mile (mi2

) 2.590 square kilometer (km2)

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3

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

gallon per minute (gal/min) 0.003785 cubic meter per minute (m3

/min)

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

/s)

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

Specific capacity

gallon per minute per foot 

[(gal/min)/ft)]

 0.2070 liter per second per meter 

[(L/s)/m]

Hydraulic conductivity

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

Hydraulic gradient

foot per mile (ft/mi) 0.1894 meter per kilometer (m/km)

foot squared per day (ft2

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

Temperature

Celsius (°C) °F = (1.8 × °C) + 32 Fahrenheit (°F)

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

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 1929).

Horizontal coordinate information is referenced to North American Datum of 1983 (NAD 83).

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

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

foot of aquifer thickness [(ft3

/d)/ft2]ft. In this report, the mathematically reduced form, foot 

squared per day (ft2

/d), is used for convenience.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius 

(μS/cm at 25 °C).
viii

 Acronyms and Additional Abbreviations

AMO Atlantic Multidecadal Oscillation

EM electromagnetic

FDEP Florida Department of Environmental Protection

GPS global positioning system

μS/cm microsiemens per centimeter

NOAA National Oceanic and Atmospheric Administration

PDSI Palmer Drought Severity Index

ROMP Regional Observation Monitoring Program

SWCFGB Southern West-Central Florida Groundwater Basin

SWFWMD Southwest Florida Water Management District

USGS U.S. Geological Survey

WWTP Waste Water Treatment Plant (Bartow)

Juvenile alligator; Gator Sink Distributary

Photo credit: P.A. Metz, USGS
ix

Acknowledgments

The authors express their appreciation to the Clear Springs Land Company for allowing 

access through their property to the State-owned Peace River corridor. Acknowledgments 

also are extended to the Florida Department of Environmental Protection and to the City of 

Bartow’s Waste Water Treatment Plant, who provided access and permitted the drilling of 

core and monitoring wells, installation of hydrologic instrumentation, and sampling of wells 

for water quality along the upper Peace River. Special acknowledgment is given to Charles 

Cook from the Florida Department Environmental Protection–Bureau of Mine Reclamation for 

providing historical and current information concerning the upper Peace River, photographic 

documentation of karst features, and assistance with field activities. The authors also thank Tom 

Jackson for his historical characterization and notable literature collection of the upper Peace 

River area. 

The authors acknowledge the assistance of Southwest Florida Water Management District 

(SWFWMD) employees Vince Pelham and Robert Parker for performing the geophysical logging 

tests, Ted Gates, who was instrumental in analyzing slug and aquifer performance tests, and 

Tim Lohner for his field support. The authors also thank SWFWMD employees Ron Basso and 

Michael Beach for their constructive technical review comments.

The authors thank Florida Geological Survey geologists Tom Scott and Harley Means for 

their insight concerning the upper Peace River geology and Clint Kromhout and Nick John for 

describing the lithologic cores used in this study. 

The authors acknowledge the assistance of U.S. Geological Survey (USGS) employees 

John Williams and Alton Anderson for performing the geophysical logging tests, and 

Laura Sacks for assisting in the isotopic analysis. Wil Causseaux and Jon Woolverton are 

recognized for the discovery of numerous important karst features and for the initial collection 

of discharge measurements in 1985 that have led to a better scientific understanding 

of streamflow losses along the upper Peace River. The authors thank Rick Spechler, 

Jonathan Gillip, and Larry Bohman for their constructive technical review comments. The 

authors also appreciate the editorial reviews of Amy Swancar, Arturo Torres, and Mike 

Deacon, which enhanced the clarity of the report, the assistance of James Tomberlin, who 

provided graphics support, and Twila Darden Wilson who designed and prepared the layout. 

The authors also express their gratitude for field support or data analysis provided by the 

University of South Florida students Jason Bellino, Troy Benson, Ann Marie Bergmann, 

Mike Caron, Geoff Fouad, Corey Guthrie, Roger Hall, Scott Orr, William Pfeiffer, Ann Sava, 

Robert Schroeder, Samer Slaiby, Makhan Virdi, and Wes Wilbanks. 
x
During this study (2002-2007 water years1

), streamflow 

was influenced by climatic conditions. The discharge in 

the river was greatest for the 2005 water year as a result of 

above-average rainfall that occurred over a 3-year period 

(2003-2005). Average annual discharge for the 2005 water 

year at the Peace River at Bartow gaging station was 545 

cubic feet per second, more than double the long-term average 

of 227 cubic feet per second for the 68 years of record. The 

discharge in the river was lowest during the 2007 water year, 

when the cumulative rainfall deficit was almost 29 inches over 

a 2-year period (measured from the long-term average rainfall 

of 54 inches). Average annual discharge for the 2007 water 

year was only 18 cubic feet per second, and was the lowest on 

record for Peace River at Bartow.

Seepage runs conducted along the upper Peace River, 

from Bartow to Fort Meade, indicate that the greatest streamflow losses occurred along an approximate 2-mile section of 

the river, beginning about 1 mile south of the Peace River at 

Bartow gaging station. Along the low-water and floodplain 

channel of this 2-mile section, there are about 10 prominent 

karst features that influence streamflow losses. Losses from 

the individual karst features ranged from 0.22 to 16 cubic 

feet per second based on measurements made between 

2002 and 2007. Along the upper part of this 2-mile section 

(in Reach 1), the largest and most consistent streamflow losses 

Abstract

The upper Peace River from Bartow to Fort Meade, 

Florida, is described as a groundwater recharge area, reflecting 

a reversal from historical groundwater discharge patterns that 

existed prior to the 1950s. The upper Peace River channel and 

floodplain are characterized by extensive karst development, 

with numerous fractures, crevasses, and sinks that have been 

eroded in the near-surface and underlying carbonate bedrock. 

With the reversal in groundwater head gradients, river water 

is lost to the underlying groundwater system through these 

karst features. An investigation was conducted to evaluate the 

hydrologic conditions that influence streamflow losses in the 

karst region of the upper Peace River. 

The upper Peace River is located in a basin that has been 

substantially altered by phosphate mining, changes in land 

use, and increases in groundwater use. These alterations have 

changed groundwater flow patterns and caused streamflow 

declines through time. Hydrologic factors that have had the 

greatest influence on streamflow declines in the upper Peace 

River include the lowering of the potentiometric surfaces of 

the intermediate aquifer system and Upper Floridan aquifer 

beneath the riverbed elevation due to below-average rainfall 

(droughts) and groundwater use, and the presence of numerous 

karst features in the low-water channel and floodplain that 

enhance the loss of streamflow. Other hydrologic factors that 

influence the decline in streamflow include changes in the 

natural drainage patterns of contributing streams to the upper 

Peace River, and altered surface sediments that affect surface 

runoff, infiltration, and baseflow characteristics.

Hydrologic Conditions that Influence Streamflow 

Losses in a Karst Region of the Upper Peace River, 

Polk County, Florida

By P.A. Metz and B.R. Lewelling

1A 12-month period (October 1 through September 30), is typically used 

by the USGS for hydrologic data analysis. The water year includes parts of 

two calendar years; for example, the 2007 water year begins on October 1, 

2006 and ends September 30, 2007.
2 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

occurred at the Ledges Sink, with measured losses ranging 

from 1 to 8 cubic feet per second. At the end of this 2-mile 

section (in Reach 2) is the most influential karst feature along 

the upper Peace River, Dover Sink, which had measured 

losses ranging from 2 to 16 cubic feet per second. The largest 

measured flow loss for all the karst features in Reaches 1 

and 2 was about 50 cubic feet per second, or about 32 million 

gallons per day, on June 28, 2002. 

Streamflow losses were related to the decline in the 

potentiometric surfaces of the intermediate aquifer system 

and the Upper Floridan aquifer below the riverbed elevation 

during below-average conditions along the upper Peace River. 

When groundwater levels were at their lowest level at the 

end of the dry season (May and June), there was an increased 

potential for streamflow losses. During this study, the largest 

streamflow losses occurred at the beginning of the summer 

rainy season when discharge in the river increased and large 

volumes of water were needed to replenish unfilled cavities 

and void spaces in the underlying aquifers. 

The response of the river to changing groundwater levels 

was different in Reach 1 than in Reach 2. In Reach 1, the 

intermediate aquifer system is hydraulically connected to the 

river, and streamflow losses during below-average conditions were proportional to water-level changes in this aquifer. 

During the dry season in Reach 1, there was an increased 

potential for streamflow losses as aquifer levels declined, and 

as aquifer levels increased during the rainy season, streamflow 

gains were noted in Reach 1. However, in Reach 2 the relation 

between streamflow losses and aquifer level declines is more 

complex. In Reach 2, the upper Peace River is connected to 

both the intermediate aquifer system and the Upper Floridan 

aquifer through a large conduit system that is associated with 

Dover Sink. Because this conduit system is very large, it can 

accommodate a large proportion of flow from the river at 

multiple river stages.

The underlying geology along the upper Peace River and 

floodplain is highly karstified, and aids in the movement and 

amount of streamflow that is lost to the groundwater system 

in this region. Numerous karst features and fractured carbonates and cavernous zones observed in geologic cores and 

geophysical logs indicate an active, well-connected, groundwater flow system. Aquifer and dye tests conducted along 

the upper Peace River indicate the presence of cavernous and 

highly transmissive layers within the floodplain area that can 

store and transport large volumes of water in underground 

cavities. A discharge measurement made during this study 

indicates that the cavernous system associated with Dover 

Sink can accept more than 10 million gallons per day (16 

cubic feet per second) of streamflow before the localized 

aquifer storage volume is replenished and the level of the sink 

stabilizes. Dover Sink stabilized when the pool of the sink rose 

to the level of the Peace River, which was about 87 feet above 

NGVD 1929, and water levels of the interconnected aquifers 

were about 78 feet above NGVD 1929.

Introduction 

The upper Peace River from Bartow to Fort Meade, 

Florida, is described as a groundwater recharge area, 

reflecting a reversal from historical groundwater discharge 

patterns that existed prior to the 1950s (fig. 1; Lewelling and 

others, 1998). Historically, the floodplain along the upper 

Peace River contained artesian wells and a second magnitude 

spring (Kissengen Spring) that discharged an average of 

20 million gallons per day (Mgal/d) into the Peace River 

(Peek, 1951; Stewart, 1966). However, hydrologic conditions 

began to change as early as the 1930s, with an increase in 

groundwater use for mining and agriculture (Peek, 1951). 

Because of this increased water use, a 40-foot (ft) decline 

in groundwater levels over a 20-year period resulted in the 

cessation of flow of the artesian wells and Kissengen Spring 

(Peek, 1951).

 The upper Peace River is located in an area where the 

river and floodplain channels are characterized by extensive 

karst development where numerous fractures, crevasses, and 

sinks have been eroded in the carbonate river channel. Because 

of the reversal in groundwater head gradients, river water is 

lost to the underlying groundwater system through these karst 

features. A trend analysis of long-term streamflow data from the 

U.S. Geological Survey (USGS) Bartow gaging station shows 

a significant decline in streamflow during the 1940s, 1950s, 

and 1960s, whereas streamflow during the 1970s remained 

statistically unchanged (Hammett, 1990). Another trend analysis 

conducted from the 1970s to 2003 indicates a continuing 

decline in streamflow (Spechler and Kroening, 2007).

Over time, declines in streamflow and groundwater 

levels have been influenced by a number of factors. Losses 

have been attributed to the following: (1) long-term rainfall 

deficits and changes in wet season rainfall patterns (Basso 

and Schultz, 2003); (2) large groundwater withdrawals that 

have lowered the potentiometric surfaces of the intermediate 

aquifer system and the Upper Floridan aquifer beneath the 

riverbed (Peek, 1951); (3) changes in the natural drainage 

patterns of contributing streams to the Peace River resulting 

from agricultural, urban, and phosphate-mining development 

(Florida Department of Environmental Protection, 2007); 

(4) strip mining of phosphate that has altered the surface sediments, which affects surface runoff, infiltration, and baseflow 

characteristics of the basin (Lewelling and Wylie, 1993); and 

(5) numerous karst features that are found in the low-water 

channel and floodplain and have enhanced the loss of perennial flow (Patton and Klein, 1989). 

The karst features along the upper Peace River play an 

important role in the loss of streamflow. A number of studies 

have documented these karst features, but little was known 

about the timing, duration, and the amount of streamflow 

that is lost to these features over varying hydrologic conditions. To gain a better understanding of the streamflow losses 

along the upper Peace River, the USGS, in cooperation 

with the Southwest Florida Water Management District 
Introduction 3

Peace River

basin

Upper Peace

River basin

LOCATION OF STUDY AREA

EXPLANATION

Lake

Wales

Lake

Hancock

Lakeland

Auburndale

Winter Haven

Bartow

Sixmile Creek

Alturas

Homeland

Fort Meade

Canal

Peace Creek Drainage

Peace

River

WETLAND—Source: Fish and Wildlife

Service, National Wetlands Inventory

polygon data, March, 2004; Universal

Transverse Mercator projection, zone 17

SURFACE-WATER ANALYSIS AREA

UPPER PEACE RIVER KARST AREA

CLEAR SPRINGS MINE AREA

98

Lake Alfred

0 5 10 MILES

82°00’ 81°45’

28°00’

27°45’

Base modified from U.S. Geological Survey digital data, 1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

0 5 10 KILOMETERS

98

17

92

Charlotte Harbor

Dover

Sink

Gator

Sink

Kissengen Spring

UPPER PEACE RIVER BASIN BOUNDARY

USGS GAGING STATION—Peace River at

Bartow

BARTOW NATIONAL WEATHER SERVICE

STATION

KISSENGEN SPRING—dry

60 60

17

27

Figure 1. Location of the upper Peace River basin and the localized study areas along the upper Peace 

River, Polk County, Florida.
4 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

(SWFWMD), began a study in 2002 to assess the effects of 

karst development and groundwater conditions on streamflow 

losses. A broader understanding of the interaction between 

surface and groundwater watersheds and their relation to 

differing geologic settings is an important component of the 

USGS Strategic Plan. The data collected and knowledge 

gained during this investigation provide an understanding of 

the specific role that karst features play in streamflow losses 

in the upper reaches of the Peace River. These data and the 

results of this study also can be used to help determine the 

minimum hydrologic conditions needed to maintain continuous flow for the ecosystems associated with the upper Peace 

River (Southwest Florida Water Management District, 2002a). 

Purpose and Scope

This report describes the hydrologic conditions that 

influence streamflow losses in a karst region of the upper 

Peace River in Polk County, Florida. For analysis purposes, 

the study area was composed of the larger upper Peace River 

basin and two smaller localized areas—the surface-water 

analysis area and upper Peace River karst area (fig. 1). The 

report provides the following information: (1) a historical 

retrospective of the hydrology and climate of the upper Peace 

River basin, (2) an analysis of land and groundwater use 

within the upper Peace River basin, (3) a description of the 

hydrogeologic framework and water chemistry of the geologic 

formations underlying the upper Peace River, (4) an inventory 

of prominent karst features along the upper Peace River karst 

area, (5) an analysis of the upper Peace River streamflow 

characteristics during the 2002 through 2007 water years, 

(6) documentation of streamflow losses to prominent karst 

features during the 2002 through 2007 water years, and (7) an 

analysis of the geologic and hydraulic connection between the 

upper Peace River and the underlying aquifers. Information 

used during this study consisted of hydrologic, lithologic, 

geophysical, and water-chemistry data collected from May 

2002 to September 2007. 

Methods of Investigation

During this investigation, the hydraulic connection 

between the upper Peace River and the underlying aquifers 

was defined using a number of hydrogeologic techniques. 

To define the rock formations and aquifer properties along the 

upper Peace River, wells were drilled in the surficial aquifer, 

intermediate aquifer system, and Upper Floridan aquifer at 

three sites along the Peace River floodplain between Bartow 

and the historic Kissengen Spring site. These wells provided 

the basis for the analysis of the hydrogeologic framework, 

hydraulic properties and groundwater flow patterns, and water 

chemistry. 

To define the hydrogeologic framework, continuous 

geologic cores were collected from land surface to depths 

ranging from about 300 to 575 ft at the three well sites. These 

cores were collected and photographed by SWFWMD and 

described lithologically by the Florida Geological Survey 

in Tallahassee, Florida. To define the hydraulic properties 

and aquifer characteristics of the rock-bearing formations 

underlying the upper Peace River basin, aquifer performance 

tests, geophysical logging, and downhole video analyses 

were conducted at all three well sites by SWFWMD (Gates, 

2009). These techniques helped determine the permeability of 

the aquifers, locations of cavities, solution conduits, fracture 

zones, the occurrence of clays, and other geologic features 

associated with the formations.

Borehole geophysical surveys were conducted at the 

three well sites to aid in the determination of aquifer properties. Geophysical logs collected included caliper, gamma, 

temperature, fluid conductivity, and fluid resistivity. In addition, electromagnetic (EM) flow and heat-pulse flowmeter 

logs were used to determine where flow zones are present 

within the hydrogeologic units at the well sites. Video logs 

also were obtained at a number of wells in the study area to 

visually inspect the aquifer within the borehole. The combined 

log information provided an understanding of well construction, contacts between hydrogeologic units, zones of inflow 

and outflow, chemical properties of water in the borehole, and 

locations of fractures and cavities. Individual log and borehole 

logging techniques are discussed in reports by Keys and 

MacCary (1971) and Keys (1990).

To understand the groundwater flow patterns along the 

upper Peace River, 12 continuous monitoring wells were used 

to define water-level trends in the surficial aquifer, intermediate aquifer system, and the Upper Floridan aquifer. In addition, wells located throughout the upper Peace River basin 

that were completed in the Upper Floridan aquifer were used 

to construct potentiometric-surface maps during wet and dry 

periods. Continuous water-level recorders also were placed on 

two prominent karst features, Dover and Gator Sinks, which 

were used to help understand the hydrologic responses of 

these features to streamflow losses.

To help determine the hydrologic relations between the 

river and the underlying aquifers, as well as the influence of 

the karst features, water levels were compared between hydrologic units. Linear regression analyses (coefficient of determination, r2) also were used to help determine the strength 

of these water-level relations. A significant statistical relation 

indicates a high degree of interconnection between the river 

and the underlying aquifers or between aquifers (r2 = 1.00). 

Water-quality and stable isotopic samples were collected 

from the Peace River and from selected wells located in the 

intermediate aquifer system and Upper Floridan aquifer. 

Water-quality data were used to define the hydrochemical 

characteristics of the river water and the underlying groundwater system. Stiff diagrams (Stiff, 1951) were used to 

compare hydrochemical characteristics among sites. Stable 

isotopic samples (deuterium and oxygen-18) were used to help 

determine flow patterns between the river and the underlying 

groundwater system. The SWFWMD collected and analyzed 

the water samples for major ions, and the USGS collected 
Introduction 5

and analyzed the water samples for isotopic composition. 

Each well was sampled four times for major ions and once 

for isotopic composition between May 2006 and March 2007. 

Established sampling protocols were used when collecting 

samples (Wilde and others, 1998; Southwest Florida Water 

Management District, 2006). 

To evaluate streamflow conditions along the upper Peace 

River, 10 USGS continuous gaging-stations, located along the 

river and adjoining tributaries, were used to measure seasonal 

changes in flow. Hundreds of discharge measurements were 

made on the river and tributaries during the 2002-2007 water 

years to establish their respective stage-discharge rating 

curves. These stage-discharge rating curves are not stable, 

and are regularly adjusted, because the hydrodynamics of a 

stream or a river change constantly (Rantz and others, 1982). 

For example, flow along the upper section of the river was 

restricted by a large accumulation of aquatic vegetation that 

choked this section of the river during the summer months. 

Field observations indicated that herbicide spraying was used 

to remove the aquatic vegetation in Saddle Creek, Peace Creek 

Drainage Canal, and the upper Peace River during this period. 

In addition, stage-discharge relations changed substantially 

after trees downed by the 2004 hurricanes were cleared from 

the channels. Therefore, ratings were adjusted periodically 

based on field-discharge measurements. 

Flow measurements were made using various methods 

depending on flow conditions. These methods included using 

portable flumes, a standard (type AA) current meter, a pygmy 

current meter, an acoustic Doppler velocimeter, and a highwater acoustic Doppler current profiler. All measurements 

were made using standard procedures and protocols (Rantz and 

others, 1982; Oberg and others, 2005). Surface and groundwater data are available in the annual USGS water data reports 

for southwest Florida (Kane and Fletcher, 2002a,b; Kane and 

others, 2003a,b; Kane, 2004a,b; 2005; Kane and Dickman, 

2005; U.S. Geological Survey, 2006b; 2007b) and from the 

USGS National Water Information System database at http://

waterdata.usgs.gov/nwis.

Data errors are inherent in discharge-rating curves 

(Rantz and others, 1982). Some of these errors may be caused 

by uncertainties associated with the measuring instruments, 

streamflow conditions, or human errors made while making 

the field measurements. Therefore, data derived from these 

curves should be used as a guide to understand variations 

in streamflow under varying hydrologic conditions, with 

the understanding that there is a degree of uncertainty and 

error associated with the discharge data. Typically, discharge 

measurements are subject to errors ranging from ±5 to 

8 percent of the measured flow (Slade and Buszka, 1994). 

Measurements in the field are rated based on a scale of good 

(±5 percent error), fair (±8 percent error), and poor (>8 percent 

error). Measurements made at extremely high-flow conditions 

have a higher error associated with the measurements (±10 

percent error). Most of the field measurements made during 

this investigation were rated as good to fair, and an error of ±5 

to 8 percent should be considered as typical when evaluating 

the data presented in this report.

To help quantify current and historical streamflow 

characteristics of the upper Peace River, daily dischargeduration hydrographs at the Peace River at Bartow gaging 

station were used. These hydrographs were based on historical 

mean daily flows for each day of the year at Peace River at 

Bartow for the period of record (1940-2007 water years). 

In addition, discharge-duration curves for the 2003-2007 water 

years were used to compare streamflow conditions among the 

following gaging stations: Peace River at Bartow, Peace River 

near Bartow, and Peace River at Clear Springs. These graphs 

represent the percentage of time during which a given value of 

discharge at each gaging station was equaled or exceeded.

To define where streamflow losses and gains in the 

upper Peace River occurred, seepage runs were conducted 

along a 13-mile (mi) segment of the river, from Bartow to 

Fort Meade (fig. 1). The seepage runs were conducted as a 

series of synoptic streamflow measurements that were made 

at selected cross sections along the 13-mi length of the river. 

When the reaches of greatest streamflow losses were identified, the scope of subsequent seepage runs was narrowed to 

an approximate 3-mi karst region (fig. 1). The seepage runs 

were performed during the dry season, when rainfall was at a 

minimum and most streamflow was derived from groundwater 

seepage (baseflow) instead of runoff. Measurement errors and 

their relation to changes in streamflow during the time period 

of the seepage run were taken into consideration. An inherent 

error of ±5 to 8 percent, typical of measurements made in a 

natural stream environment (Rantz and others, 1982), was 

considered appropriate for the analyses of these seepage runs. 

Changes in discharge greater than this associated error (±5 

percent) were considered as net changes. Net gains or losses 

within measurement error were not considered significant.

Prominent karst features in the low-water channel and 

floodplain were documented by global positioning system 

(GPS) latitude-longitude coordinates, and surface orientations and dimensions were measured. During the study, these 

features were found to be continuously changing because of 

scour and fill streamflow depositional processes, and photographs were taken to document these changes. For example, 

the effects of three major hurricanes passing through the area 

in 2004 caused some of the karst features to fill with sand, and 

in 2007 other observed karst features were enlarged due to 

increased scouring from river flow. 

Several methods were used to quantify streamflow losses 

to the karst features. One method involved making discharge 

measurements in the channel directly above where the water 

flowed into the karst feature. The second method involved 

measuring discharge in the sections above and below the 

karst feature, and calculating the flow loss as the difference 

between these measurements. Measurements that bracket the 

karst features had the higher degree of uncertainty because 

of possible seepage losses through the riverbed between 

measurement sections. 
6 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Previous Investigations

Previous investigations have contributed to the understanding of the hydrogeology, water use, and karst development in the upper Peace River basin. Many studies that 

describe the general geology of central Florida have references 

to Polk County. Some of the early investigators include 

Matson and Sanford (1913), Stringfield (1936), Applin and 

Applin (1944), Cooke (1945), Vernon (1951), and Carr and 

Alverson (1959). 

Stewart (1966) describes the geologic characteristics of 

Polk County and also provides detailed information pertaining 

to the hydrology. A section of Stewart’s report also describes 

solutions features, cavities, and sinkholes in Polk County. 

Spechler and Kroening (2007) present an updated appraisal of 

the groundwater and surface-water resources of Polk County 

and describe the current hydrologic trends. 

Updated descriptions of geology and hydrogeology 

of the Floridan aquifer system and the intermediate aquifer 

system in the study area are in reports by Ryder (1985) and 

Miller (1986). Scott (1988) describes the lithostratigraphy 

of the Hawthorn Group of Miocene age; Duerr and others 

(1988) define the hydrogeologic framework of the intermediate aquifer system; and Knochenmus (2006) evaluates the 

hydrogeologic framework, hydraulic properties, and chemical 

characteristics of the intermediate aquifer system. Especially 

pertinent to this study is the report by Gates (2009), which 

describes the aquifer properties at three monitor well sites 

along the upper Peace River that were drilled as part of this 

investigation.

Several investigators have discussed the karst hydrology 

of the upper Peace River basin. The study by Vernon (1951) 

suggests that the extensive fracturing in the rocks in Polk 

County greatly influences the groundwater hydrology. Stewart 

(1966) suggests that major cavernous development, which 

occurs along these fractures zones, enhances the watertransmitting ability of the underlying limestone. Sinclair and 

others (1985) characterizes the study area as being susceptible 

to sinkhole development and describes how various types of 

sinkholes form. Basso (2003) describes groundwater conditions and surface-water/groundwater interactions in the upper 

Peace River basin. 

A number of investigations describe the locations of the 

karst features in the upper Peace River karst area and how 

these features affect the local hydrology. Patton (1981) and 

Patton and Klein (1989) mapped more than 90 sinkholes 

and discuss sinkhole formation and its effect on Peace River 

hydrology. McQuivey and others (1981) presented an experiment where rhodamine dye was injected into a major sink 

(Dover Sink), and described how the dye traveled south 

through an area where the intermediate aquifer system and 

Upper Floridan aquifer are interconnected. Lewelling and 

others (1998) documented that the greatest streamflow losses 

in the entire Peace River basin occur in the upper reaches of 

the Peace River. Knochenmus (2004) documented the upper 

Peace River karst features and defined the flow losses during a 

low-water period.

Numerous reports discuss water use and the effects of 

groundwater pumping in Polk County. Peek (1951) related 

the cessation of flow of Kissengen Spring to the excessive 

use of groundwater for mining operations. Kaufman (1967), 

Robertson and Mills (1974), and Hutchinson (1978) describe 

the effects of groundwater pumping in the upper Peace River 

basin. The first inventory of well records and other waterresource data in Polk County was presented in a report by 

Stewart (1961). Current groundwater withdrawals and trends 

in groundwater use in Polk County are discussed in reports by 

Marella (2004), Marella and Berndt (2005), and Spechler and 

Kroening (2007). 

Brown and Tighe (1991) and Lewelling and Wylie 

(1993) discuss the effects of mining on the hydrology of the 

Peace River basin. The Peace River Cumulative Impact Study 

by Florida Department of Environmental Protection (2007) 

assesses the cumulative impacts of certain anthropogenic and 

natural stresses on historical changes in streamflow in the 

Peace River, and discusses rainfall and streamflow trends in 

the upper Peace River basin.

Upper Peace River Basin 

Characteristics

The Peace River is formed by the merging of Saddle 

Creek and the Peace Creek Drainage Canal, which both rise 

in the uplands of east and central Polk County (fig. 1). From 

the confluence of these streams, the river flows southward for 

105 mi to Charlotte Harbor. The upper Peace River basin, as 

described in this study, extends south from an area near Lake 

Alfred to near Fort Meade (fig. 1). The upper basin drains 

about 790 square miles (mi2), and encompasses an area about 

one-third of the size of the entire Peace River basin. 

The upper Peace River basin partly resides within the 

Polk Upland, which is a poorly drained plateau that contains 

flatwoods, wetlands, and lakes (White, 1970; Brooks, 1981) 

(fig. 2). Adjacent to the upper Peace River and within the 

described basin are the Winter Haven Ridge and three northwest to southeast trending ridges: the Lake Henry, Gordonville, 

and Lakeland Ridges (White, 1970; Brooks, 1981). The 

easternmost extension of the upper Peace River basin is the 

Lake Wales Ridge, which is the highest and longest of the 

ridges that are present on the Florida peninsula. These ridges 

are remnant shoreline features and are the dominant landforms 

in the upper Peace River basin (Schmidt, 1997). These sandy 

ridges are internally drained with rapid recharge, and are prone 

to sinkhole development (Brooks, 1981). Land-surface elevation ranges from about 80 ft near Fort Meade to about 305 ft 

above NGVD 1929 along the Lake Wales Ridge.
Upper Peace River Basin Characteristics 7

0 5 10 MILES

EXPLANATION

82°00’ 81°45’

28°00’

27°45’

Base modified from U.S. Geological Survey digital data, 1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

Lakeland

Homeland

Auburndale

Lake

Wales

Fort Meade

Lake Alfred

Bartow

Lakeland Ridge

Lake Henry Ridge

Lake Wales Ridge

Polk Upland

Winter Haven Ridge

Gordonville Ridge

PHYSIOGRAPHY

Alturas

Lake

Hancock

Peace

River

Peace Creek Drainage

Canal

Sixmile

Creek

0 5 10 KILOMETERS

UPPER PEACE RIVER

BASIN BOUNDARY

SINKHOLE

Figure 2. Physiographic subdivisions and location of sinkholes in the upper Peace River basin.

Sinkholes are prevalent throughout the upper Peace 

River basin and are in various stages of development, 

including ancient stable depressions and those formed 

recently. More than 140 sinkholes have been documented in 

the upper Peace River basin (fig. 2), and more than 90 sinkholes, fractures, and crevasses (not shown in fig. 2) have been 

documented along the upper Peace River floodplain (Patton, 

1981). Karst features identified along the Peace River bed are 

discussed in a subsequent section (Karst Features along the 

Upper Peace River). 

The sinkholes in the upper Peace River basin range in 

size from 10 to greater than 100 ft in diameter, and in depth 

from 5 to 200 ft below land surface. The shallow depressions 

usually contain swamps or cypress domes, whereas deeper 

depressions extending as much as 200 ft below land surface 

commonly infill with sand and water and form sinkhole lakes. 

The numerous closed basin lakes and sinkholes of the Winter 

Haven and Lake Wales Ridges indicate solutional activity in 

the geologic past. Collectively, the sandy ridges interspersed 

with sinkhole-formed lakes produce a setting capable of 
8 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

storing and recharging rain and shallow groundwater to 

deeper aquifers. Recharge is greater than 10 inches per year 

(in/yr) along the Lakes Wales and Winter Haven Ridges but is 

lower along the upper Peace River basin (0 to 5 in/yr) due to 

increased confinement between the surficial aquifer and Upper 

Floridan aquifer (Aucott, 1988; Yobbi, 1996). 

Climate

Warm, wet summers and relatively mild, dry winters and 

springs characterize the subtropical climate of the study area. 

Rainfall varies seasonally, and more than half the annual rainfall typically occurs during the summer months (June through 

September). Rainfall can be unevenly distributed throughout 

the study area during the summer rainy season, because it is 

derived from localized, convective thunderstorms. Winter 

rainfall is more evenly distributed, because storms generally 

come from frontal air masses that move from north to south 

across the State. 

The long-term (1900-2007) average annual rainfall from 

the National Weather Service Bartow station is about 54 in. 

(National Oceanic and Atmospheric Administration, 2007). 

Rainfall was summarized by water years in this study so that 

comparisons could be made between rainfall and streamflow. 

Yearly rainfall and the departure from the long-term average 

rainfall by water year are shown in figures 3A and 3B, respectively. The lowest rainfall recorded was about 32 in. in the 

1950 water year, and the greatest was about 83 in. in the 2003 

water year. Some of the lowest annual rainfall totals for the 

107-year period of record occurred during this investigation; 

rainfall at the Bartow station was about 40 and 37 in. in water 

years 2006 and 2007, respectively.

Hydrologic conditions in the study area are directly 

related to seasonal variations in rainfall. For example, at the 

beginning of the rainy season, a large percentage of the rainfall 

is incorporated into surface and groundwater storage (Basso 

and Schultz, 2003). At the end of the rainy season, surfaceand groundwater levels are high and much of the rainfall 

goes directly to runoff (Ross and others, 2001). On average, 

monthly rainfall at Bartow is lowest in November, followed 

by December, January, and April, whereas monthly rainfall 

is highest in July, followed by June, August, and September. 

Analysis of the last 11 years of rainfall record (1997-2007) 

indicates a reduction in rainfall during June and also during 

the latter part of the rainy season (September). 

Assessing the long-term regional rainfall cycles gives 

insight to natural and anthropogenic hydrologic changes in 

streamflow and groundwater levels (Basso and Schultz, 2003). 

One such climatic cycle, the Atlantic Multidecadal Oscillation 

(AMO), helps describe the historical climatic changes of 

the study area (Gray and others, 1997; Landsea and others, 

1999; Enfield and others, 2001). The AMO is defined by the 

warming or cooling surface temperatures of the oceans that 

affect rainfall patterns (Gray and others, 1997). The warm and 

cool phases of the AMO are shown in figure 3B. Research 

also suggests that during periods of cooler ocean temperatures 

in the Pacific Ocean, less rainfall occurs during the winterearly spring season across peninsular Florida and, conversely, 

warmer ocean temperatures in the Atlantic Ocean produce 

more summer rainfall (Enfield and others, 2001; Basso and 

Schultz, 2003; Kelly, 2004).

The 5-year moving average of the departure of rainfall 

from the period of record indicates a trend in the AMO and 

its relation to rainfall within the study area (fig. 3B). For 

example, during the warm AMO period from 1925 through 

1969 (fig. 3B), there were periods of above-average rainfall 

and concurrent increases in tropical storm activity. During the 

cool AMO period from 1970 through 1995 (fig. 3B), periods 

of below-average rainfall were concurrent with decreased 

tropical storm activity (Gray and others, 1997; Landsea and 

others 1999). The current (1996-present) warm AMO phase is 

characterized by increased tropical storm activity in peninsular 

Florida. 

Climatic conditions had a major influence on the 

hydrology of the study area, and the period of this investigation (2002-2007 water years) can be summarized as one of 

climatic extremes. In 2002, a severe drought was already 

underway, with a cumulative rainfall deficit of more than 

31 in. for the 1999-2002 water years. Conditions changed 

between the 2003 and 2005 water years, with a cumulative 

rainfall excess of more than 43 in. for this period (fig. 3B). 

During a 6-week period from August through September 

2004, three major hurricanes (Charley, Frances, and Jeanne) 

crossed the study area. However, climatic conditions again 

changed between 2006 and 2007, with below-average rainfall 

leading to another drought period. During the 2006 and 2007 

water years, the cumulative rainfall deficit was almost 29 in., 

causing reduced streamflow in the upper Peace River. During 

these water years, a majority of the rainfall deficit occurred 

during the spring and summer months.

The Palmer Drought Severity Index (PDSI) for the 

Bartow station was used to evaluate the climatic conditions 

of the study area from October 2000 to September 2007. The 

PDSI is a measure of dryness, and is based on a model of soil 

moisture that accounts for rainfall and temperature (Palmer, 

1965). This index uses zero as the normal value, whereas 

droughts are shown as negative numbers with -4 (and below) 

as the extreme drought condition, and wet periods are shown 

as positive numbers with +4 (and above) as the extreme. 

Weekly PDSI readings averaged to monthly conditions 

show the severity of the drought in 2000 that continued into 

the summer of 2002 for the Bartow area (fig. 4). The PDSI 

indicates wet conditions from July 2002 to August 2005, 

and moderate drought conditions from September 2005 to 

September 2007 (fig. 4).

In addition to rainfall, evaporation also plays an important role in the hydrology of the study area. Evaporation 

rates are high in Florida, and are greater than in most other 

areas of the country (Farnsworth and others, 1982). High 

evaporation rates in this subtropical climate are primarily due 

to high solar radiation and water temperatures. Long-term 
Upper Peace River Basin Characteristics 9

DEPARTURE—In inches. Departure of the annual rainfall from the average

rainfall of 54.12 inches from the Bartow rainfall station for the water years

1900-2007

5-YEAR MOVING AVERAGE—Of the annual departure of rainfall for the water

years 1900 to 2007

PHASE CHANGE FOR THE ATLANTIC MULTIDECADAL OSCILLATION—(Gray

and others, 1997, Enfield and others, 2001, and Landsea and others, 1999)

100

90

80

70

60

50

40

30

20

10

0

30

20

10

0

-10

-20

-30

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2007

DEPARTURE FROM

AVERAGE RAINFALL, IN INCHES ANNUAL RAINFALL, IN INCHES

EXPLANATION

Warm Atlantic

Multidecadal

Oscillation

Cool Atlantic

Multidecadal

Oscillation

Cool Atlantic

Multidecadal

Oscillation

Warm Atlantic

Multidecadal

Oscillation

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2007

(A)

(B)

Figure 3. (A) Annual rainfall at Bartow, Florida (1900-2007), and (B) rainfall departure, 5-year moving average of this departure, and 

changes in the Atlantic Multidecadal Oscillation (location of weather station is shown in fig. 1).

estimates of annual shallow lake evaporation range from 48 to 

59 in. in central Florida, and can vary depending on climatic 

conditions (Farnsworth and others, 1982; Lee and Swancar, 

1997; Amy Swancar, USGS, written commun, 2008). Many 

clay-settling areas exist along the upper Peace River as a result 

of phosphate-mining extractions, and the clay-lined bottoms of 

these areas limit their recharge capacity. Water in these ponds 

typically evaporates instead of recharging the groundwater 

system, which is a loss of water from the upper Peace River 

basin that did not occur before mining operations began. 
10 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Hydrography

The upper reach of the Peace River, near the confluence 

of the Peace Creek Drainage Canal and Saddle Creek, is 

characterized by a narrow and shallow streambed that contains 

shifting sand and sluggish, tannic-colored streamflow. Pond 

cypress trees line the banks at the confluence, but after a 

short distance the banks are marked by large piles of mined 

tailings from previous phosphate-mining operations. For the 

next 13 mi downstream, numerous elevated clay-settling areas 

border the area alongside the floodplain, and surface-water 

drainage to the upper Peace River is limited to phosphate-mine 

outfalls, stormwater ditches, or reclaimed stream channels. 

Historically, a number of streams contributed to the flow 

in the upper reaches of the Peace River. However, much of the 

predevelopment drainage system has been altered by phosphate mining and agricultural activities. Maps of the upper 

Peace River basin created during 1850-1855 show the natural 

streams prior to their alteration by phosphate mining (fig. 5). 

The original stream channels are shown for Saddle Creek, 

Peace Creek, Bear Branch, Sixmile Creek, Cedar Branch, 

Hamilton Branch, Barber Branch, and an unnamed tributary. 

These streams show dendritic drainage patterns and channels 

that are longer than their current configurations. 

Figure 6 compares the present and historical hydrography, contrasting the extent of altered stream patterns. Peace 

Creek, which is now referred to as Peace Creek Drainage 

Canal, has been substantially altered to accommodate urban 

and agricultural runoff and flood control. Channelization of 

Peace Creek has caused sluggish flows or stagnation during 

medium to low-flow conditions, because the natural streambeds were replaced by wide, flat ditches or canals that have 

little to no gradient. Saddle Creek, Sixmile Creek, Cedar, 

Bear, Hamilton, and Barber Branches, as well as an unnamed 

tributary (now referred to as Phosphate Mine Outfall CS-8), 

were altered and reclaimed by the phosphate-mining process. 

The meandering natural streambeds with sloping gradients 

were typically replaced by flat ditches and clay-settling areas 

that can store large quantities of water. Runoff is typically 

stored in these clay-settling areas before discharging to the 

river. As a result of these impoundments and changes in the 

natural dendritic flow patterns of these streams, the amount of 

flow contributing to the upper Peace River has been reduced 

(Florida Department of Environmental Protection, 2007). 

Land Use

Land use within the upper Peace River basin is diverse 

and continues to change as the population grows and the 

economy evolves (fig. 7). Major land-use categories in the 

upper Peace River basin include extracted mined lands (36 

percent), agriculture (26 percent), urban development (12 

percent), wetlands and forests (11 percent), water bodies 

(11 percent), and industrial and commercial (4 percent) 

(Southwest Florida Water Management District, 2007). 

Polk County is the eighth most populous county in the 

State, and 2005 population estimates indicate that the population is expected to increase in the foreseeable future (Office 

of Economic and Demographic Research, 2005). The largest 

population in the upper Peace River basin occurs in the 

northern part of the study area, with Lakeland and Winter 

Haven being the largest cities in the county. Urban growth 

is greatest around these cities, with development extending 

beyond the city boundaries. Municipalities located near 

the upper Peace River include Bartow, Homeland, and Fort 

Meade (fig. 7).

Polk County had the second largest amount of agricultural land in the State in 2005, estimated at 626,634 acres (ac) 

(Polk County Farm Bureau, 2005). In 2004, Polk County 

ranked first in the State in the amount of commercial citrus 

groves and fourth in the number of beef and dairy cattle. In the 

upper Peace River basin, more than 125,000 ac is designated 

as agricultural land. The largest agricultural land-use categories include tree crops (citrus) and cropland and pastureland 

(Southwest Florida Water Management District, 2007) 

About 15 percent of the area of Polk County has been 

mined for phosphate rock, and the county ranks first in 

the State (2005) for phosphate production (Polk County 

Department of Economic Development, 2005). Phosphate has 

6

4

2

0

-2

-4

-6

DROUGHT SEVERITY

2001 2002 2003 2004 2005 2006 2007

4.00 or more Extremely wet

3.00 to 3.99 Very wet

2.00 to 2.99 Moderately wet

1.00 to 1.99 Slightly wet

0.50 to 0.99 Incipient wet spell

0.49 to -0.49 Near normal

EXPLANATION

-0.50 to -0.99 Incipient dry spell

-1.00 to -1.99 Mild drought

-2.00 to -2.99 Moderate drought

-3.00 to -3.99 Severe drought

-4.00 or less Extreme drought

2000

Figure 4. Palmer Drought Severity Index for the study area for 

the 2001 to 2007 water years.
Upper Peace River Basin Characteristics 11

been mined within the upper Peace River basin since the 

late 1800s. In 1881, the first discovery of phosphate deposits 

occurred in the Peace River bed near Fort Meade. This 

discovery initiated the mining of the largest identified deposit 

of phosphate rock in the world, known as the “Bone Valley 

Deposit” (Florida Institute of Phosphate Research, 2006b). 

The phosphate deposits found in the river are called river 

pebbles and were extracted from bars of coarse pebbles in 

and along the upper Peace River during the late 1800s. When 

these deposits began to be depleted and its extraction became 

too costly, prospecting for land-pebble deposits was initiated 

in 1890 along the headwaters of the Peace River near Bartow 

(Lanquist, 1955). 

Phosphate mining for land pebbles played an important 

role in the development of many of the cities and towns 

located along the upper Peace River, such as Bartow, Homeland, and Fort Meade. During the 1920s, 1930s, and 1940s, 

phosphate mining was concentrated near the cities of Bartow 

and Fort Meade. Mining operations expanded to areas 

near Homeland by the 1950s, and to the Clear 

Springs and Kissengen Spring area by the 1960s. 

Much of the area around the upper Peace River was 

mined before the State of Florida required mandatory 

land reclamation in 1975; therefore, some of the land 

surrounding the upper Peace River has not been 

reclaimed (Michelle Harmeling, FDEP, Bureau of 

Mine Reclamation, written commun., 2008). 

Phosphate mining for land pebbles involves using huge 

draglines and buckets to remove vegetation and overburden 

that is about 30 to 40 ft thick in the study area (Brown, 2005). 

Draglines and buckets are used to create cuts in the landscape 

that are 200 to 300 ft wide and up to several thousand feet 

long (Yon, 1983). The dragline digs out what is known as the 

matrix, which consists of phosphate rock, sand, and clay. The 

matrix is then dumped in a pit where high-pressure water guns 

create a slurry by a process called beneficiation. This slurry is 

then pumped to the beneficiation plant for further processing 

(Florida Institute of Phosphate Mine Research, 2006b). At the 

plant, the phosphate is separated from the sand and clay, the 

clay is then pumped to a clay-settling area, and the sand is 

typically pumped back to the site during reclamation. The 

postmined landscape is generally a combination of waterfilled troughs and steep-sloped piles of sand and clay. The 

topography is often described as resembling a “moonscape” 

(Brinkmann and Koenig, 2007). 

Historical photos from the State Library and 

Archives of Florida; Department 

of Commerce collection.

Slurry created by hydraulic pressure (above) then piped to beneficiation plant (below).

Phosphate mining for river pebbles along the Peace River, late 1800s.

Altered landscape created by phosphate mining.

Upper Peace River Basin Characteristics 11
12 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Figure 5. Historical hydrography (1850-1855) of the upper Peace River basin (base maps from the Florida 

Department of Environmental Protection, 2003). 

Lake

Lena

Lake

Ariana

Lena Run

Saddle Creek

Peace

Bear Branch

Cedar Branch

Barber

Branch

Sixmile Creek

Peace i R ver

Creek

Unnamed Tributary

Saddle Creek

0 1 2 3 MILES

WETLANDS AND FORESTED AREAS 0 1 2 3 KILOMETERS

HISTORICAL HYDROGRAPHY (1850-1855)

EXPLANATION

Lake Hancock

N
Upper Peace River Basin Characteristics 13

WETLANDS AND FORESTED AREAS

HYDROGRAPHY ALTERED BY MINING PROCESSES

HISTORICAL HYDROGRAPHY (1850-1855)

HYDROGRAPHY 1985

EXPLANATION

Drainage Canal

0 1 2 3 MILES

0 1 2 3 KILOMETERS

Lake

Lena

Lake

Ariana

Lena Run

Lake Hancock

Saddle Creek

Peace

Bear Branch

Cedar Branch

Barber

Branch

Sixmi r le C eek

Peace River

Creek

Unnamed Tributary

Saddle Creek

Figure 6. Historical (1850-1855) and current (1985) hydrography of the upper Peace River basin (base maps from 

the Florida Department of Environmental Protection, 2003).
14 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Figure 7. Land use in the upper Peace River basin, 2005.

0 5 10 MILES

82°00’ 81°45’

28°00’

27°45’

Base modified from U.S. Geological Survey digital data, 1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

0 5 10 KILOMETERS

"

"

"

"

"

"

"

"

Alturas

Lakeland

Homeland

Lake

Wales

Lake

Alfred

Lake

Hancock

Winter

Haven

Bartow

Fort Meade

Peace

River

EXPLANATION

LAND USE

UPPER PEACE RIVER BASIN

BOUNDARY

Agricultural and open land

Industrial and commercial

(includes transportation

and utilities)

Mining

Urban development

(includes residential and

recreational)

Water

Wetlands and forests

HYDROGRAPHY
Upper Peace River Basin Characteristics 15

Within the upper Peace River basin, the dominant 

reclaimed landforms produced during surface mining are 

clay-settling areas that can cover hundreds of acres and exceed 

40 ft in depth. Many of these clay-settling areas line both 

sides of the upper Peace River floodplain from the cities of 

Bartow to Fort Meade. Typically, a reclaimed clay-settling 

area is built by constructing a high perimeter dam around a 

mined area, forming a containment to hold the clay-waste 

slurry (Lewelling and Wylie, 1993). During construction of 

the clay-settling area, most of the disturbed overburden that 

was removed from the mined pit is used to build the perimeter dam to provide more volume for clay storage. The clay 

slurry that is separated from the phosphate matrix during the 

beneficiation process is pumped into the clay-settling area 

to dewater, settle, and consolidate. These clay-settling areas 

possess entirely different physical properties, in terms of water 

storage and transmission, than the landscape prior to mining 

(Brickmann and Koenig, 2007). 

Soils

The surface soils of the upper Peace River basin are 

composed of fine sands along the ridges and uplands, fine 

sands and loams along the riverine floodplain, mucky fine 

sand in depressional areas, altered soils in urban areas, and 

sandy-clay soils in mined areas (Southwest Florida Water 

Management District, 2002b; fig. 8). About 54 percent of 

the upper Peace River basin is underlain by upland soils 

that are moderately sloping and excessively to moderately 

well drained, which allows for rapid infiltration. Soils of the 

riverine floodplain and in depressional areas are frequently 

flooded, have little to no slope, and have a high water 

table (where present); these soils are moderately to poorly 

drained, providing moderate infiltration. The depressional 

and frequently flooded areas make up about 10 percent of the 

upper Peace River basin.

 Mined soils border both sides of the Peace River 

floodplain and make up the remaining 36 percent of the upper 

Peace River basin (fig. 8). The sandy-clay soils of mined sites, 

or arents, are less pervious because of the increase in clay 

content at the surface horizons that tends to limit surface infiltration (Lewelling and Wylie, 1993). Postmining areas contain 

a large amount of clay waste byproduct, which typically occupies about 40 to 60 percent of the postmined landscape (Yon, 

1983). Arent soil types include haplaquents, hydraquents, 

udorthents, gypsum-land complex, and urban-land complex. 

Because of the low hydraulic conductivity of clay, groundwater recharge and movement through a clay-settling area can 

be substantially less than soils under natural conditions. 

The floodplain of the upper Peace River near the confluence of Saddle Creek and Peace Creek Drainage Canal, and 

along sections of the river within the Clear Springs Mine area, 

was mined before 1975 when mandatory reclamation was instituted. Field observations indicate that during low- to- moderate 

rainfalls, water tends to pond on these unreclaimed impervious 

soils and evaporation is assumed to be the major avenue of 

water loss from these areas. Additionally, shrinkage of the 

consolidating clays can cause depressional surface features 

to form, increasing ponding and evaporation, and reducing 

runoff (Lewelling and Wylie, 1993). During higher rainfall 

events, however, water tends to run off as sheetflow. Additional 

research is needed to understand how these altered soil characteristics affect drainage patterns in the upper Peace River basin. 

Groundwater Use 

The upper Peace River basin is located in the Southern 

West-Central Florida Groundwater Basin (SWCFGB), about 

5,000-mi2, which relies heavily on groundwater for water 

supply (Southwest Florida Water Management District, 

1988; Barcelo and Basso, 1993) (fig. 9A). During the study 

period, groundwater withdrawn for water supply from this 

groundwater basin ranged from about 480 (2005) to 642 

(2006) Mgal/d (Mike Kelley, SWFWMD, written commun., 

2009) (fig. 9B). 

Groundwater use in Polk County totaled 212 Mgal/d in 

2005, of which 98 percent was from the Upper Floridan aquifer 

(Marella, 2009). The total groundwater withdrawn from the 

upper Peace River basin during 1992-2005 averaged about 

113 Mgal/d (Mike Kelley, SWFWMD, written commun., 2007) 

(fig. 9C). The greatest amount of groundwater withdrawn in 

the upper Peace River basin was during years of below-average 

rainfall in 1992, 1998, and 2000. The least amount of groundwater withdrawn was during years of above-average rainfall in 

2003-2005 (fig. 3B).

The major groundwater-use categories for the 1992-

2005 period are shown in figure 9D. The largest average 

groundwater use during this period was for agriculture 

(44.7 Mgal/d), public supply (38.6 Mgal/d), industrial/

commercial (19.0 Mgal/d), mining (6.7 Mgal/d), and 

recreation (3.7 Mgal/d). Pumpage was constant for most 

purposes from year-to-year, except for agriculture and mining. 

Agriculture exceeded all other uses between 1992 and 2002, 

reaching a maximum during 2000 because of a severe drought 

that increased the need for irrigation. Agricultural water use 

declined from a high of 61 to 20 Mgal/d in 2000 and 2005, 

respectively, as a result of a number of wet years (2003-2005) 

that reduced the need for irrigation. In addition, in 2004 

Hurricanes Charley and Frances passed directly through the 

study area, causing citrus tree loss and the resultant decrease 

in irrigation. Groundwater use for mining declined from 

16.7 to less than 0.5 Mgal/d in 1992 and 2005, respectively 

(fig. 9D) as operations moved to areas south and west of the 

upper Peace River basin. 

In 2005, major use categories were public supply 

(39 Mgal/d), agriculture (20 Mgal/d), industrial/commercial 

(16 Mgal/d), recreational (3 Mgal/d), and mining (0.5 Mgal/d) 

(fig. 9D). The spatial distribution of this pumpage by 

groundwater-use categories for the year 2005 is shown in 
16 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Figure 8. Generalized soil types in the upper Peace River basin.

"

"

"

"

"

"

"

"

"

0 5 10 MILES

82°00’ 81°45’

28°00’

27°45’

Base modified from U.S. Geological Survey digital data, 1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

0 5 10 KILOMETERS

A A’

ROMP 59

WELLS

ROMP 60 WELL

Auburndale

Alturas

Lakeland

Homeland

Lake Wales

Lake

Alfred

Lake

Hancock

Winter

Haven

Bartow

Fort Meade

Peace

River

A A’ Fine sand

Mucky fine sand

Water

Fine sand to sandy clay loam (frequently flooded)

Urban land complex

Arents (soil alterations due to urban and mining alterations

which includes a sandy and clayey substratum, gypsum

land, clayey haplaquants and hydraquents, excavated

udorthents, and an urban land and water complex)

EXPLANATION

SOIL TYPE UPPER PEACE RIVER BASIN BOUNDARY

LOCATION OF PROFILE LINE SHOWN IN

FIGURE 21
Upper Peace River Basin Characteristics 17

figure 10 (Mike Kelley, SWFWMD, written commun., 2007). 

In addition, the amount of groundwater withdrawn during 

2005 for the individual wells is shown in figure 10. 

Public supply was the largest groundwater use during 

2005, because agricultural use was lower during this wet 

year. Public-supply wells are concentrated near larger cities 

such as Lakeland, Bartow, Auburndale, and Winter Haven. 

Public-supply wells usually are concentrated in clusters and 

pumpage for individual wells ranges from less than 0.0001 

to 1.4 Mgal/d (fig. 10). Agriculture was the second largest 

groundwater user in 2005, with more than 600 wells used 

for irrigation (2005) throughout the upper Peace River basin 

(Mike Kelley, SWFWMD, written commun., 2007). Citrus 

irrigation dominates this groundwater use at 92 percent of 

all agricultural-use categories (row crops, sod and plant 

nursuries, and pasture). Groundwater withdrawals from 

individual citrus irrigation wells ranged from 0.00001 to 

0.40 Mgal/d in 2005. Industrial and commercial was the third 

largest use category, with phosphate and citrus processing 

using the majority of this water, and use ranged from 0.002 

to more than 5 Mgal/d. The largest amount of groundwater 

withdrawn (5 Mgal/d) in the upper Peace River basin in 2005 

was for a phosphate processing plant, which is considered 

industrial use. Recreational groundwater use included lawn, 

garden, and golf course irrigation and augmentation of lakes; 

water withdrawn from the individual wells ranged from 

0.0002 to 0.23 Mgal/d in 2005.

900

800

700

600

500

400

300

200

100

0

1950 1960 1970 1980 1990 2000 2010

Estimated groundwater use (excludes Charlotte, Glades, and Lee counties)

ESTIMATED GROUNDWATER USE, SOUTHERN

WEST-CENTRAL FLORIDA GROUNDWATER BASIN,

IN MILLION GALLONS PER DAY

POLK

MANATEE

HARDEE

DESOTO

HILLSBOROUGH

HIGHLANDS SARASOTA

CHARLOTTE GLADES

PINELLAS

PASCO

LEE

(A)

Southern

West-Central

Florida

Groundwater

Basin

Upper Peace

River basin

(Written communication Southwest Florida Water Management District, 2007) (Written communication Southwest Florida Water Management District, 2007)

70

60

50

40

30

20

10

0

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Agriculture

Industrial/Commerical

Mining/Dewatering

Public supply

Recreational

GROUNDWATER USE, IN MILLION GALLONS PER DAY

ESTIMATED GROUNDWATER USE IN THE UPPER

PEACE RIVER BASIN, IN MILLION GALLONS PER DAY160

140

120

100

80

60

40

20

0

(C) (D) 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Estimated use

10 year moving

average

(B)

(Written communication Southwest Florida Water Management District, 2009)

GULF OF MEXICO

Figure 9. (A) Location of the Southern West-Central Florida Groundwater Basin, (B) estimated groundwater use in the 

Southern West-Central Florida Groundwater Basin and (C) in the upper Peace River basin, and (D) estimated groundwater 

use by category in the upper Peace River basin, 1992 through 2005.
18 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

0 5 10 MILES

82°00’ 81°45’

28°00’

27°45’

Base modified from U.S. Geological Survey digital data, 1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

0 5 10 KILOMETERS

"

"

"

"

"

"

"

60 "

Alturas

Lakeland

Homeland

Lake

Wales

Lake Alfred

Lake

Hancock

Winter

Haven

Bartow

Fort Meade

Peace

River

EXPLANATION

MAJOR WATER-USE

CATEGORIES

UPPER PEACE RIVER

BASIN BOUNDARY

Agriculture

Industrial and commercial

Mining

Public supply

Recreation

GROUNDWATER PUMPAGE

—In million gallons per

day. Size of circle is

proportional to the amount

of ground-water withdrawn

Less than 0.1

0.1 to <0.5

0.5 to <1.0

1.0 to <5.0

 5.0

(Written communication Southwest Florida Water Management District, 2007)

Figure 10. Major water-use categories and pumpage distribution for groundwater withdrawn from the Upper Floridan aquifer 

in the upper Peace River basin, 2005.
Geologic Framework 19

Geologic Framework

Many investigators have contributed to the understanding 

of the geologic framework of the study area. Prior to this 

study, however, limited information was available about the 

geology immediately adjacent to the Peace River and how 

the geology affects hydrologic conditions along the river. 

This investigation focuses on the geology that spans from 

the Eocene through Holocene ages, including from oldest 

to youngest, the Avon Park Formation, Ocala Limestone, 

Suwannee Limestone, Hawthorn Group, and undifferentiated 

surficial deposits. The stratigraphic units, hydrogeologic 

units, and generalized lithologic descriptions are presented in 

figure 11.

The geologic units along the upper Peace River consist 

of sand, clay, marl, phosphate grains and pebbles, and 

carbonate rocks that were deposited primarily in an open or 

restricted marine environment. Deposition of each formation was followed by a period of erosion that resulted in the 

development of solution cavities and formational surface 

irregularities. Carbonates are susceptible to postdeposition 

erosional processes that include weathering, dissolution, 

and fracturing, which enhances the permeability within and 

between these units. Of particular interest to this study are the 

Suwannee Limestone, the Hawthorn Group, and undifferentiated surficial deposits, because these formations have the 

greatest potential for interaction with the upper Peace River. 

A geologic cross section along the upper Peace River from 

north to south is shown in figure 12.

SERIES STRATIGRAPHIC UNIT GEOLOGY AND LITHOLOGY HYDROGEOLOGIC UNIT

Holocene and

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Undifferentiated

surficial deposits Sand and fossil fragments Surficial aquifer

system

(surficial aquifer)

Sand, silt, and clay

Hawthorn

Group

Peace River Formation

Arcadia Formation

Sand, clay, marl, phosphate

grains and pebbles,

limestone and dolostone.

Fossils common.

Intermediate aquifer system1

Tampa

Member Nocatee

Member

Suwannee Limestone

Ocala Limestone

Avon Park Formation

Oldsmar Formation

Cedar Keys Formation

Limestone, sandy limstone

and sand. Phosphatic in part.

Dolostone beds and fossils

common.

Upper Floridan aquifer

Middle

confining unit

Lower

Floridan aquifer

Sub-Floridan

confining unit

Floridan aquifer system

Limestone and dolostone with

some intervals containing

inclusions of gypsum

and anhydrite

Limestone and dolostone with

beds of gypsum and anhydrite

Bone Valley Member

Middle

semiconfining unit

Cypresshead

Formation

Confining unit

Confining unit

Confining unit

Zone 2, upper Arcadia aquifer

Zone 3, lower Arcadia aquifer

Upper permeable

zone

Semiconfining unit

Lower permeable

zone

1

A proposed revision by DeWitt and Mallams (2007) and Mallams and DeWitt (2007) replaces zone 2 and zone 3 from Knochenmus (2006) with the upper and lower Arcadia aquifers,

respectively. This revision also proposes to rename the intermediate aquifer system in southwestern Florida to the Hawthorn aquifer system (excluding the upper and lower confining

units). There is not a current consensus, however, on the use of “Hawthorn aquifer system,” so in this report only the proposed upper and lower Arcadia aquifer names are used.

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

2002; Sepulveda, 2002; Basso and Hood, 2005; Knochenmus, 2006; DeWitt and Mallams, 2007; Mallams and DeWitt, 2007; and Spechler

and Kroening, 2007).
20 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

The lowermost geologic units of interest in the study area 

are composed of a thick sequence of carbonate rocks that vary 

in composition based on their depositional history (Randazzo 

and Jones, 1997). The Avon Park Formation is characterized 

by alternating layers of soft to well-indurated fossiliferous 

limestone that typically is highly fractured and cavernous 

(Stewart, 1966). Above the Avon Park Formation is the Ocala 

Limestone, which contains two distinct geologic units. The 

lower unit contains limestone and dolomite and is characterized as granular, well-indurated, dense, and fossiliferous. The 

upper unit is composed of soft, pure limestone that contains 

numerous fossils and is poorly indurated. The Suwannee 

Limestone of Oligocene age overlies the Ocala Limestone and 

is composed of interbedded, sand-size limestone grains and 

soft calcareous mud and sand. This limestone also is fossiliferous and contains abundant bryozoans, small mollusks, and 

large echinoids (Stewart, 1966). 

Overlying these carbonate units is a sequence formed 

under a variety of depositional environments that produce a 

complex geologic assemblage of carbonates and siliciclastic 

sediments during the late Oligocene to Miocene (Randazzo 

and Jones, 1997). These environments of deposition included 

open marine, shallow water, coastal marine, fluvial, and 

estuarine (Gilboy, 1985). This complex sequence of sedimentary deposits forms the highly heterogeneous Hawthorn Group 

(Missimer, 2002). 

SUWANNEE LIMESTONE

AVON PARK FORMATION

OCALA LIMESTONE

HAWTHORN GROUP

100

50

50

100

150

200

250

300

350

400

450

500

550

Geologic core LW1P

4 5 6 7

UPPER FLORIDAN AQUIFER

INTERMEDIATE

AQUIFER SYSTEM

NGVD

1929

62.66

82.24

DRY 83.62

83.11

57.88

57.62

62.94

54.99

FEET

1 WELL NUMBER AND

Well number (1) refers to index number

in table 5.

WATER LEVEL–

Water level in feet above

NGVD 1929. Gray section is open or

screened interval for well.

62.66

EXPLANATION

Gator Sink

Peace River

56.58

GATOR SINK SITE AND WATER LEVEL

stimated depth is 40 feet below land

surface. Water level in feet above

NGVD 1929

–

E

0 1.0 MILES

1.0 KILOMETERS

B

SOUTH

B’

8 9

LW1P

well

nest

1 2 3

Geologic core LW3P

Geologic core LW4P

0

Vertical scale greatly exaggerated

100

50

50

100

150

200

250

300

350

400

450

500

550

NGVD

1929

UNDIFFERENTIATED

SURFICIAL DEPOSITS

LW3P

well

nest

LW4P

well

nest

56.58

NORTH

FEET

Peace River

Peace River

Peace River

DIRECTION OF GROUNDWATER FLOW.

Figure 12. Geologic cross-section along the upper Peace River and water levels for study wells that indicate

recharging conditions (June 1, 2007). (Geologic cross-section line shown in figure 13.) Figure 12. Geologic cross-section along the upper Peace River and water levels for study wells that indicate recharging 

conditions (June 1, 2007) (line of geologic section is shown in fig. 13B).
Geologic Framework 21

Within the study area, the Hawthorn Group contains 

the Arcadia and the Peace River Formations. The Arcadia 

Formation underlies the Peace River Formation and consists 

primarily of carbonates with some siliciclastic sediments 

(Scott, 1988). Carbonates of the Arcadia Formation are 

sandy, phosphatic, and in some places clayey. The Arcadia 

Formation includes two members, the Tampa Member and 

the Nocatee Member. The Peace River Formation consists of 

beds of green-gray clay and dolomitic clayey sand to sandy 

clay that contain abundant pellets and fine pebble-sized 

phosphate (Scott, 1988). The Peace River Formation includes 

the Bone Valley Member, which is characterized by a mixture 

of phosphate gravel, sand-sized phosphate, quartz sand, and 

clay (Scott, 1988). The sediments that overlie the Peace River 

Formation consist of undifferentiated surficial deposits of the 

Pleistocene and Holocene series. These sediments consist of 

fine-to medium-grained quartz and phosphatic sands, silt, and 

clay. Undifferentiated surficial deposits have been disturbed 

over much of the upper Peace River basin during mining of 

the phosphate-rich Bone Valley Member.

The top of the Avon Park Formation was detected at 

about 400 ft below land surface at the LW1P site and at 500 ft 

below land surface at the LW4P (Kissengen Spring) site. The 

top of Avon Park Formation consisted of medium-grained, 

poorly indurated limestone in a calcilutite matrix. The dominant fossils identified in these rocks included the foraminifera 

Dictyoconus americanus and the echinoid Neolaganum dalli. 

Cores extended 105 ft into the Avon Park Formation at LW1P 

and 85 ft at LW4P, and the limestone varied from grainstone, 

packstone, mudstone, to wackestone.

The Ocala Limestone, as described from the cores, varied 

from highly weathered, poorly indurated, calcareous mud 

to moderate -to well-indurated mudstone and wackestone. 

The fossil that defines the Ocala Limestone, Lepidocyclina 

ocalana, was present in most core samples. Calcareous mud 

was more prevalent at the LW1P site than at LW4P site, where 

the lower section contained many layers of well-indurated 

limestone (Gates, 2009). The average thickness of the Ocala 

Limestone, based on the two core sites (LW1P and LW4P), 

was about 160 ft.

Geologic Cores 

Continuous geologic cores were 

collected at three sites along the upper 

Peace River within a span of about 

3.5 mi (figs. 12 and 13). The cores 

were collected by the wire-line coring 

method; a detailed description of the 

method is presented in Gates (2009). 

The three core sites are the LW1P site 

located at the Bartow Waste Water 

Treatment Plant (WWTP), the LW3P 

site located at the Clear Springs Mine 

dragline crossing, and the LW4P site 

located near the historic Kissengen 

Spring. Continuous cores extended 

into the Avon Park Formation at the 

LW1P and LW4P sites and into the 

Ocala Limestone at the LW3P site. 

Analysis of the cores indicates that the geology varies 

along the upper Peace River, especially within the Hawthorn 

Group, which is in direct contact with the river. The multiple 

interbedded layers of carbonate and siliciclastic sediments 

indicate a complex erosional and depositional history that 

occurred during the late Oligocene and Miocene time period. 

Cores show a wide variety of weathered carbonate rocks, 

interlayered with siliciclastic sediments. The core lithologies 

include sand and clay, dolomite or dolostone, and limestone 

that were further identified as packstone, mudstone, wackestone, grainstone, and calcilutite. Most of the limestone 

identified was rich in calcareous mud and is classified as a 

mudstone and wackestone (Dunham, 1962). 

Overlying the Ocala Limestone 

is the Suwannee Limestone, which 

in cores was composed of highly 

weathered, friable limestone and 

dolostone that was poorly consolidated, calcareous and chalky, and 

contained some clay stringers and 

numerous fossils at varying depths. 

A majority of the limestone identified in the Suwannee Limestone 

was rich in calcareous mud and was 

identified as mudstone and wackestone. The average thickness of the 

Suwannee Limestone, based on the 

three cores, was about 130 ft. 

The Hawthorn Group that 

overlies the Suwannee Limestone is 

composed of the Arcadia and Peace 

River Formations. The Hawthorn 

Group contains less limestone and 

more siliclastic sediments than the 

underlying Suwannee Limestone. The Hawthorn Group is 

exposed at places along the streambed and is in direct connection with the river. The cores that penetrated the Hawthorn 

Group are described as sequences of weathered dolomite 

that is fractured and contains pinpoint vugs, voids, and 

numerous fossils casts and molds that aid in the development 

of secondary porosity within this unit. Interspersed within the 

Hawthorn Group are sequences of stiff clays, sands, phosphate 

pebbles and grains, and thin layers of weathered limestone.

 The Hawthorn Group has an average thickness of about 

130 ft based on the three cores. The Arcadia Formation has 

an average thickness of about 120 ft, and is composed mostly 

of fossiliferous dolostone that contained numerous fossil 

Geologic core samples.
22 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

0 1 2 3 MILES 0 0.5 1 MILE

0 1 2 3 KILOMETERS 0 0.5 1 KILOMETERS

Bartow

Homeland

Fort

Meade

Highland

City

Bartow

(A)

(B)

INSET (B)

1

2

3

81°50’ 81°48’

27°54’

27°52’

28°00’

58’

56’

54’

52’

50’

48’

27°46’

81°54’ 52’ 50’ 48’ 81°46’

Bear

Sixmile

Creek

Barber

Branch

Phosphate

CS-8

Mine

Outfall

Clear Springs

IAS well

Peace River

at Bartow

Peace River at

Clear Springs

Pit Lakes

ROMP 59

wells

Area of inflow

when Peace River

stage is above

94 feet

Dover Sink

LW1P

Monitor

site

LW4P Monitor site

Kissengen Spring (dry)

LW3P

Monitor

site

1-3

4-7

8-9

B

B’ Otter Sink Tom’s Sink

10

11-12

15

Gator

Sink

16

Lake

Hancock

River

Saddle Creek

Bear Branch

1

Phosphate Mine Outfall CS-8

Peace River at Homeland

Peace River

at Bartow

Peace River

near Bartow

Peace River at

Clear Springs Sixmile

Creek

Kissengen

Spring (dry)

Barber

Branch

Peace River

at Fort Meade

Homeland

well no. 4

Wastewater

Treatment Plant

(WWTP)

13

14

P

a

eace Creek Drain ge Canal

Homeland

well no. 9

2

3

4

Peace

River

Peace

River

Peace River

near Bartow

Branch

EXPLANATION

MINED AREA

HYDROLOGY ASSOCIATED WITH MINED AREAS

OPEN WATER

LINE OF GEOLOGIC SECTION—section shown in figure 12

REACH AND REACH NUMBER

CLEAR SPRINGS MINE BOUNDARY

GEOLOGIC CORES AND MONITORING WELLS DRILLED DURING

STUDY—number refers to table 5

KISSENGEN SPRING—dry

MONITORING SINK—number refers to table 5

MONITORING WELL—number refers to table 5

LOCATION OF GROUNDWATER SAMPLES

LOCATION OF SURFACE-WATER SAMPLES

KARST FEATURE

USGS STREAMFLOW-GAGING STATION AND NAME

Peace

1

1-3

15

10

98

60

60

17

630

555

640

98

98

17

17

559

60

98

98

17

Base modified from U.S. Geological Survey digital data,

1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

Base modified from U.S. Geological Survey digital data,

1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

B B’

Sixmile Creek

60

Pit

Lakes

Sixmile

Creek

Figure 13. Location of (A) stream gaging stations, (B) geologic cores, sinks, and groundwater monitoring and water-quality 

sampling sites.
Geologic Framework 23

Limestone outcrop along the dry river bottom downstream from 

Ledges Sink. Photo credit: P.A. Metz, USGS

the movement of even larger volumes of water, which in 

turn dissolves more limestone and dolomite. Eventually, the 

openings and passageways coalesce to form conduits and or 

cavities that continue to enlarge by further solution development. Groundwater flow velocities typically are much greater 

in these karst conduit systems than in porous media (Ryder, 

1985).

Limestone starts to dissolve at a pH below 7.0, and acidic 

industrial wastewaters may have accelerated the dissolution 

of the rocks underlying the upper Peace River during the early 

1950s when some of the tributaries to the upper Peace River 

were contaminated by acid mine waste (Lanquist, 1955). 

The Florida State Board of Health collected 156 samples for 

pH determinations from 1950 to 1953 at the Bear Branch 

bridge on U.S. Highway 17, which flows into the Peace River 

about 326 ft above the State Road (SR) 60 bridge. The pH 

values of the tributary water ranged from 2.2 to 4.9, and averaged 4.6 (Lanquist, 1955). The Florida State Board of Health 

also collected 162 water samples for pH determinations from 

the Peace River at Bartow during this same time period. The 

pH of the river water ranged from 4.8 to 7.7, averaging 6.5. 

The USGS collected 200 river samples at the Peace River at 

Bartow gage between 1963 and 1999. The pH of these samples 

ranged from 5.6 to 10.0, averaging 6.9.

Important factors for determining the potential effects of 

these acidic waters on the river and karst dissolution are the 

residence time and the amount of flow in the river. During 

one of the years when acid mine waste was discharged (1950 

water year), rainfall was the lowest amount for the 107 years 

of record (32 in.) and the discharge in the river was below 

average for most of the year. When rainfall and discharge in 

the river are low, there is an increased potential for limestone 

dissolution, because less discharge equates to less dilution of 

the acidic waters. In addition, reduced discharge indicates that 

streamflow is slower in the upper Peace River, increasing the 

time of contact with the dissolving limestone. Low pH water in 

the river may have enhanced limestone dissolution during this 

period, but the extent of this dissolution is difficult to quantify. 

molds and casts. The Peace River Formation is thin, with an 

average thickness of only 10 ft. This formation is composed 

mainly of limestone that contains vugs, fossil molds, and fossil 

dissolution cavities. 

The undifferentiated surficial sediments are the uppermost formation in the cores. These sediments consist of quartz 

and phosphatic sands, silt and organics, and varying amounts 

of clay. This unit is thin, with an average thickness of about 

6 ft (LW1P and LW3P). Surficial deposits were absent at the 

LW4P site (Kissengen Spring). 

Karst Development 

Sinkholes are common throughout this mantled karst 

landscape and contribute to the highly variable geologic 

framework of the area. Sinkholes form when limestone 

dissolves and cavities develop in the subsurface limestone. 

As the cavities expand, the overlying sand and clay subside 

into the solution openings, forming a depression in the land 

surface. The more than 90 sinkholes documented by Patton 

(1981) were along about a 6-mi reach of the high and lowwater channel of the upper Peace River, and most of the 

sinkholes were located along the upper half of this reach. Over 

half of these sinkholes were larger than 10 ft in diameter, with 

10 percent exceeding 40 ft in diameter. 

Although sinkholes develop naturally, their unusual 

density along the upper Peace River can be explained, in part, 

by the increased use of groundwater in the area (Kaufman, 

1967; Patton, 1981; Sinclair, 1982; Newton, 1986; Shock 

and Wilson, 1996; Tihansky, 1999). Many of these sinkholes 

may have been formed after abrupt declines in groundwater 

levels during the 1940s through 1975, when large volumes 

of groundwater were pumped for phosphate mining. A large 

decline in groundwater levels removes the hydraulic support 

of overburden sediments lying above cavities, which results in 

the formation of sinkholes (Newton, 1986). Similar large-scale 

clustered sinkhole developments have been documented near 

well fields where large volumes of groundwater have been 

withdrawn for public supply (Sinclair, 1982; Tihansky, 1999; 

Metz and Sacks, 2002). In addition, changes in the Upper 

Floridan aquifer from discharge to recharge conditions may be 

related to the increased karst activity.

Karst solution features as described in this investigation 

consist of piping features, fissures, cracks, crevices, conduits, 

cavities, karst windows, sinks, and fractures in the limestone 

or dolomite bedrock. The two most important factors in 

development and expression of karst features are the amount 

of precipitation in the region and the solubility of the bedrock 

(Weary and others, 2008). Karst development occurs as a 

result of chemical dissolution of the soluble layers in the limestone and dolomite by slightly acidic water (a pH below 7.0).

 The karst landscape is formed by circulating acidic 

waters that enlarge the natural fractures and pores within 

the limestone or dolomite, thus increasing the permeability 

of the rock. This enhanced secondary porosity allows for 
24 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Hydrogeology

The principal hydrogeologic units in the study area are, 

in descending order, the surficial aquifer, intermediate aquifer 

system, and Upper Floridan aquifer (fig. 11). The uppermost 

unit, the surficial aquifer, is an unconfined sand and clayey 

sand aquifer. Underlying this unit is the mixed carbonate and 

siliciclastic intermediate aquifer system, which contains a 

number of water-bearing units. The lowermost unit, the Upper 

Floridan aquifer, is a highly productive carbonate aquifer and 

is the principal source of freshwater in west-central Florida 

(Miller, 1986). 

Surficial Aquifer

The surficial aquifer is a permeable hydrogeologic unit, 

contiguous with land surface, that principally consists of 

unconsolidated to poorly indurated clastic deposits (fig. 11; 

Southeastern Geological Society, 1986). This unit is commonly 

referred to as the surficial aquifer system where more than one 

permeable zone is present or where the deposits are interbedded. 

In this report, the deposits are considered to form a single 

homogeneous aquifer, and are referred to as the surficial aquifer. 

The surficial aquifer is recharged by rainfall that infiltrates the permeable deposits and percolates downward to the 

water table. The surficial aquifer is an important component 

of the groundwater system, because it provides the means 

for the temporary storage of infiltrating water that eventually 

percolates down to the underlying aquifers or moves laterally 

to areas of discharge. 

In some areas of the upper Peace River basin, the 

surficial aquifer does not exist, because the surface sediments 

have been removed by strip mining for phosphate. Where 

the surficial aquifer is present, the thickness is variable in 

the upper Peace River basin, ranging from less than 10 ft to 

more than 200 ft along the sandy Lake Wales Ridge (Spechler 

and Kroening, 2007). Beneath the ridges of the upper Peace 

River basin (Lake Henry, Gordonville, Lakeland, and Lake 

Wales Ridges; fig. 2), the surficial aquifer has a large storage 

capacity and provides substantial recharge to the underlying 

aquifers. Along the Peace River floodplain, however, the 

surficial aquifer is thin to nonexistent, limiting the amount 

of infiltration and recharge. Where the water table is present 

along the floodplain, the depth to the water table is about 5 

to 10 ft below land surface. During extended dry periods, the 

surficial aquifer may go dry. The surficial aquifer has a low 

specific capacity along the upper Peace River floodplain. 

A specific-capacity test was performed at the LW3P well on 

February 7, 2007. The well was constructed to a depth of 

12 ft below land surface with 7 ft of open screen. The well 

was pumped dry during the test at a rate of less than 1 gallon 

per minute (gal/min). The calculated specific capacity was 

0.3 gal/min per foot of drawdown (Gates, 2009).

Intermediate Aquifer System

The intermediate aquifer system includes all waterbearing units (aquifers) and confining units between the 

overlying surficial aquifer and the underlying Upper Floridan 

aquifer (Duerr and others, 1988). Within the study area, the 

intermediate aquifer system consists of three or more hydrogeologic units (fig. 11): (1) a clayey and pebbly sand, clay, 

and marl upper confining unit that separates the uppermost 

water-bearing unit in the intermediate aquifer system from the 

surficial aquifer; (2) one to two water-bearing units composed 

primarily of carbonate rocks, sand, and discontinuous beds 

of sand and clay; and (3) a sandy clay and clayey sand lower 

confining unit that lies directly over the Upper Floridan 

aquifer (Ryder, 1985). The thickness of the intermediate 

aquifer system from the three cores ranged from about 100 ft 

to less than 170 ft. The thickness of the intermediate aquifer 

system in the upper Peace River basin ranges from about 100 

to 300 ft (Spechler and Kroening, 2007). 

Slug tests were performed to determine the horizontal 

hydraulic conductivity of the confining and water-bearing 

units (aquifers) of the intermediate aquifer system. Slug tests 

provide a localized estimate of hydraulic conductivity or transmissivity in the near vicinity of a well. Slug test procedures 

and results are discussed in Gates (2009). Slug tests performed 

on the upper confining unit indicate that the unit has a low 

horizontal hydraulic conductivity value of about 0.3 foot per 

day (ft/d) (Gates, 2009).

Underlying the upper confining unit are two water-bearing 

units called the upper and lower Arcadia aquifers (DeWitt 

and Mallams, 2007) (fig. 11). This aquifer nomenclature is a 

proposed revision by DeWitt and Mallams (2007) and Mallams 

and DeWitt (2007) that replaces zone 2 and zone 3 from 

Knochenmus (2006) with the upper and lower Arcadia aquifers, 

respectively. This revision also proposes to rename the intermediate aquifer system in southwestern Florida to the Hawthorn 

aquifer system (excluding the upper and lower confining 

units), in keeping with aquifer naming guidelines in Laney and 

Davidson (1986). There is not a current consensus, however, on 

the use of “Hawthorn aquifer system,” so in this report only the 

proposed upper and lower Arcadia aquifer names are used. 

Slug tests of these aquifers indicated an increase in the 

horizontal hydraulic conductivity compared to the overlying 

confining unit that ranged from 2 to 42 ft/d. Transmissivities 

of the upper Arcadia aquifer reported from aquifer performance tests at wells LW1P and LW4P were 5,000 to 125,000 

feet squared per day (ft2/d), respectively (Gates, 2009). The 

wide range of transmissivity values for the intermediate 

aquifer system indicates its formational heterogeneity. 

The area of greatest transmissivity occurs within 

the upper Arcadia aquifer (zone 2; fig. 11) at the LW4P 

(Kissengen Spring) well. During coring at this well, a large 

cavity was detected between 40 and 55 ft below land surface. 

This cavity also was encountered at approximately the same 

depth while drilling two nearby monitor wells and a watersupply well. The cavity appears to be horizontally extensive 
Hydrogeology 25

across the 100-ft wide well site, which is located about 100 ft 

northeast of the historical Kissengen Spring site. The high 

transmissivity value of 125,000 ft2/d for the intermediate 

aquifer system occurred within the depth interval from 30 to 

76 ft below land surface. The high transmissivity and presence 

of large conduits indicate an active cavernous flow system 

within the upper intermediate aquifer system in this part of 

the upper Peace River floodplain. Figure 14 shows a nearby 

outcrop of the Arcadia Formation that depicts the secondary 

porosity of the weathered carbonate unit. 

The lower confining unit lies at the base of the intermediate aquifer system and, to some extent, hydraulically 

separates the intermediate aquifer system from the Upper 

Floridan aquifer (fig. 11). The lower confining unit has a low 

vertical hydraulic conductivity and, consequently, retards 

interaquifer flow. Slug tests limited to the lower confining 

unit were performed at all three sites drilled for this study, and 

indicate horizontal hydraulic conductivity values that ranged 

from about 0.003 to 0.7 ft/d (Gates, 2009).

Within the study area, the intermediate aquifer system 

is used as a source of water for irrigation and public and 

domestic supply. Wells open to the intermediate aquifer system 

commonly yield less than 300 gallons per minute (gal/min) 

(Wilson, 1977). The yield to wells and total withdrawals of 

water from the intermediate aquifer system is much less than 

those for the underlying Upper Floridan aquifer, and represents 

only 1 percent of the groundwater withdrawn in Polk County.

Upper Floridan Aquifer

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

is a vertically continuous sequence of carbonate rocks of 

generally high permeability (fig. 11). In the study area, the 

Floridan aquifer system consists of two aquifers: the Upper 

Floridan aquifer, which generally contains freshwater, and 

the Lower Floridan aquifer, which contains highly mineralized water. The Upper Floridan aquifer consists of the 

Suwannee Limestone, the Ocala Limestone, and the Avon Park 

Formation of the Oligocene and Eocene series. The top of the 

Upper Floridan aquifer in the study area coincides with the top 

of the Suwannee Limestone. The base of the aquifer is defined 

as the first occurrence of vertically persistent intergranular 

evaporites in the Avon Park Formation (Miller, 1986). The 

thickness of the Upper Floridan aquifer is about 1,000 ft 

within the study area (Basso, 2003). 

The Upper Floridan aquifer consists of limestone and 

dolomite that have solution-enlarged fractures. The Upper 

Floridan aquifer is the most productive and widely used aquifer 

in the Southern West-Central Florida Groundwater Basin, 

and supplies more than 10 times the amount of water that 

is pumped from the intermediate aquifer system (Metz and 

Brendle, 1996). The Upper Floridan aquifer is used extensively 

for irrigation, industrial and commercial, public, recreational, 

and domestic supplies; large capacity wells can yield up to 

5,000 gal/min (Southwest Florida Water Management District, 

1994). Some of the wells in the study area that are completed 

in the Upper Floridan aquifer also are open to the intermediate 

aquifer system (Metz and Brendle, 1996). 

Aquifer performance tests were conducted at the LW1P 

and LW4P wells to determine the hydraulic properties of the 

Upper Floridan aquifer. The aquifer performance tests were 

conducted in the open intervals between 95 to 235 ft below 

land surface at the LW1P well, and between 151 to 310 ft 

below land surface at the LW4P well. Both of these test 

intervals coincide with the Suwannee Limestone, which, as 

described from the cores, is composed of highly weathered, 

poorly indurated, silt-size limestone and calcareous mud 

and sand. Transmissivity values within this unit ranged from 

13,000 ft2/d at the LW4P well site to 56,000 ft2/d at the LW1P 

well site (Gates, 2009).

The geophysical logs for the three monitor well sites 

drilled for this project are shown in figures 15 through 17. 

Analysis of the gamma log indicates high levels of gamma 

activity in the Hawthorn Group within the intermediate 

aquifer system because of the clay matrix that surrounds the 

dominate rock type within this unit. Below the intermediate 

aquifer system, there is a decrease in clay content and a 

resultant decrease in gamma activity, which denotes the top 

of the Upper Floridan aquifer. The top of the Upper Floridan 

aquifer, as determined from the gamma logs, is about 105 ft 

below land surface at the LW1P well (fig. 15), 170 ft below 

land surface at the LW3P well (fig. 16), and 160 ft below land 

surface at the LW4P well site (fig. 17). 

In addition to gamma logs, caliper and video logs were 

used to delineate the contacts between hydrogeologic units and 

locations of fractures and cavity zones. Contacts between units 

are generally more weathered and fractured than within units 

and are commonly indicated by an increase in the borehole 

diameter, as shown in the caliper log. The three caliper logs 

Figure 14. Secondary porosity of the Arcadia Formation within the 

intermediate aquifer system (Gator Sink). Photo credit: P.A. Metz, 

USGS
26 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Figure 15. Geophysical logs for well site LW1P.

FLUID RESISTIVITY,

IN OHM-METERS

21 22 23 68 69 70

TEMPERATURE,

IN DEGREES

FAHRENHEIT

0

20

40

60

80

100

120

140

160

180

200

220

240

260

0

GAMMA, IN COUNTS

PER SECOND

-5 5

Ambient flow

(downward flow)

Pumping

(upward flow)

CALIPER, IN INCHES

5 10 15

LITHOLOGY

DEPTH, IN FEET BELOW LAND SURFACE

Polyvinyl

chloride (PVC)

casing to 17

feet

EXPLANATION

Sand

Dolostone

Fossils and fossil molds

Ambient Ambient

400

FLOW, IN GALLONS PER MINUTE

Ambient

While pumping 25 gallons per minute

While pumping 56 gallons per minute

-10 10

FLOW, IN GALLONS PER MINUTE

Ambient

While pumping 25 gallons per minute

Vugs and pin point vugs

Limestone (packstone and grainstone)

Calcareous limestone (mudstone and wackestone)

Surficial aquifer

Intermediate

aquifer

system

Upper Floridan

Aquifer

0

0
Hydrogeology 27

FLUID CONDUCTIVITY,

IN MICROSIEMENS

PER CENTIMETER

350 400 500 69 71 72

TEMPERATURE,

IN DEGREES

FAHRENHEIT

0

GAMMA, IN COUNTS

PER SECOND

-13 13

CALIPER, IN INCHES

5 10 18

LITHOLOGY

400

FLOW, IN GALLONS PER MINUTE

While pumping 13 gallons per minute

-0.25 0.25

FLOW, IN GALLONS PER MINUTE

Ambient

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

320

15 450 70

Ambient flow

(downward flow)

Pumping

(upward flow)

Polyvinyl

chloride (PVC)

casing to 170

feet

Ambient

Ambient

Surficial aquifer

Intermediate

aquifer

system

Upper Floridan

Aquifer

Pumping

EXPLANATION

Sand

Dolostone

Fossils and fossil molds

Clay

Vugs and pin point vugs

Limestone (packstone and grainstone)

Calcareous limestone (mudstone and

wackestone)

DEPTH, IN FEET BELOW LAND SURFACE

0

0

Figure 16. Geophysical logs for well site LW3P.
28 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida DEPTH, IN FEET BELOW LAND SURFACE

VOID

Intermediate

aquifer

system

Upper Floridan

Aquifer

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

320

Pumping

Ambient

Ambient

Pumping

Caliper log for

the intermediate

aquifer system

well; well depth

77 feet, cased

depth 31 feet

Caliper log for

a temporary

Upper Floridan

aquifer well;

depth 310 feet,

cased depth

feet150

EXPLANATION

Sand

Dolostone

Fossils and fossil molds

Clay

Vugs and pin point vugs

Limestone (packstone and grainstone)

Calcareous limestone (mudstone and

wackestone)

FLUID CONDUCTIVITY,

IN MICROSIEMENS

PER CENTIMETER

400 500 71 72

TEMPERATURE,

IN DEGREES

FAHRENHEIT

0

GAMMA, IN COUNTS

PER SECOND

-100 100

CALIPER, IN INCHES

5 10 25

LITHOLOGY

175

FLOW, IN GALLONS PER MINUTE

While pumping 100 gallons per minute

-0.25 0.25

FLOW, IN GALLONS PER MINUTE

Ambient

450

Ambient flow

(downward flow)

Pumping

(upward flow)

15 20

0

0

Figure 17. Geophysical logs for well site LW4P.
Hydrogeology 29

indicate an increase in the caliper trace at the top of the Upper 

Floridan aquifer, which signifies a weathered fractured zone. 

A downhole video camera was used to verify these zones. 

Confirming the results of the drilling cores, the caliper 

log for the intermediate aquifer system well at the LW4P 

site (fig. 17) indicated a large cavity at a depth of 38 to 53 ft 

below land surface. A downhole video camera was then used 

to identify the extent of the pervasive cavity at a similar depth 

for three nearby temporary wells used during drilling and two 

nearby monitor wells. All logs indicated that a cavity exists at 

this depth over a distance of at least 100 ft. Near the LW4P site 

is the extinct Kissengen Spring, the newly formed Otter Sink, 

and Tom’s Sink (fig. 13B), which may also be part of this 

fracture system. Numerous casts, molds, vugs, and fractures 

were visible in the video logs. 

Results from the flowmeter logs during ambient 

conditions indicate downward flow in the boreholes for the 

LW1P and LW3P wells, and no detectable flow in the LW4P 

well borehole. Flowmeter logs during pumping conditions 

indicate that flow moved up the boreholes and exited the 

borehole at formation contacts. Results from EM flow logs 

at LW1P indicate that water moves downward within the 

borehole during non-pumping conditions. During pumping 

conditions, flow was observed at permeable zones within 

the hydrogeologic units. For example, EM flow logs at the 

LW1P well, which has an open interval of 17 to 235 ft below 

land surface, indicate that most flow in the borehole occurs 

at discrete zones located 20 to 25, 60 to 70, and 90 to 100 ft 

below land surface. A comparison of geologic cores and EM 

flow logs indicates that these flow zones are in areas where the 

carbonates are fractured and weathered. 

Potentiometric Surface

Predevelopment water levels are considered to be the 

levels of the potentiometric surface of the Upper Floridan 

aquifer prior to any groundwater usage (Johnston and others, 

1980). Predevelopment levels ranged from 120 ft in the northern 

part of the upper Peace River basin to 80 ft in the southern 

part (fig. 18A). Prior to development, regional groundwater 

flow through the upper Peace River basin was mostly from 

the north toward the south-southwest. Current potentiometricsurface levels (May 2007) indicate a range from 120 ft in the 

northern part to 50 ft in the southern part of the basin, with 

the largest declines occurring in the west-central part of the 

upper Peace River basin near Bartow (fig. 18B). The current 

regional groundwater flow paths (May 2007) have shifted to 

a more westerly direction through the basin compared to the 

predominate north-south trending predevelopment flow paths. 

Potentiometric-surface maps of the intermediate aquifer 

system are difficult to construct, because existing control 

wells are finished in multiple aquifers producing composite 

potentiometric-surface levels. Water levels in the intermediate 

aquifer system in the study area also are more localized and 

are influenced by the heterogeneous geology and by several 

topographic highs, including the Lake Wales Ridge to the east 

POTENTIOMETRIC SURFACE CONTOUR—Shows level that water would

have stood in tightly cased wells tapping the Upper Floridan aquifer.

Interval 10 feet. Datum is NGVD 1929

GROUNDWATER FLOW DIRECTION

UPPER PEACE RIVER BASIN BOUNDARY

EXPLANATION

120

90

80

70

60

100

110

50

100

May 2007

0 5 10 MILES

5 10 KILOMETERS

82°00’ 81°45’

28°00’

27°45’

Base modified from U.S. Geological Survey digital data, 1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

Predevelopment

levels

110

100

120

80

90

(A)

Lake

Wales

Lakeland

Winter Haven

Bartow

Homeland

Fort Meade

Lake

Hancock

River

Peace

0

82°00’ 81°45’

28°00’

27°45’

Base modified from U.S. Geological Survey digital data, 1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

(B)

River

Peace

0 5 10 MILES

5 10 KILOMETERS

Lake

Wales

Lakeland Winter

Haven

Bartow

Homeland

Fort Meade

0

Lake

Hancock

Figure 18. (A) Predevelopment (modified from Johnston and others, 

1980) and (B) May 2007 potentiometric-surface levels (modified from 

Ortiz, 2008a) and regional groundwater flow patterns of the Upper 

Floridan aquifer within the upper Peace River basin.
Otter at Otter Sink. Photo credit: P.A. Metz, USGS

and Lakeland Ridge to the west (fig. 2). Based on wells open 

only to the lower Arcadia aquifer in the vicinity of the upper 

Peace River, groundwater flow generally moves from the 

nearby ridges toward the river. 

Long-Term Trends in Groundwater Levels

In the upper Peace River basin, the groundwater levels 

in the Upper Floridan aquifer have declined (currently about 

50 ft) from predevelopment levels because of historical 

groundwater use. Long-term water-level records indicate that 

the declines started in the late 1930s when large quantities of 

groundwater were used for phosphate-mining processes (Peek, 

1951; Hutchinson, 1978; Lewelling and others, 1998). This 

large potentiometric-surface decline resulted in the cessation of flow from Kissengen Spring and minor springs that 

discharged from the Upper Floridan aquifer and intermediate 

aquifer system (Peek, 1951; Stewart, 1966; Lewelling and 

others, 1998) (fig. 19A). In addition, artesian wells at the 

headwaters of the Peace River near Saddle Creek ceased to 

flow in the late 1950s (Stewart, 1966).

A hydrograph of the Upper Floridan aquifer Regional 

Observation Monitoring Program (ROMP) well ROMP 60 

shows that the long-term decline in water levels continued 

into the mid-1970s (fig. 19B; location of well is shown in 

fig. 8). The peak of phosphate production in the upper Peace 

River basin occurred during the mid-1970s, when groundwater 

pumpage for phosphate mining was estimated to be about 

270 Mgal/d (Spechler and Kroening, 2007). An increase in 

water levels after the mid-1970s coincided with the period 

of time when the phosphate-mining industry started waterconservation practices (Spechler and Kroening, 2007).

 Statistical analysis of the water levels in the Upper 

Floridan aquifer shows about a 20-ft rise in levels from the 

mid-1970s to 2007. This rise may be a result of a combination 

of factors that include the reduction in groundwater pumpage 

for phosphate during the past decades, climatic conditions, and 

improved conservation by agriculture. Although mining in the 

area has declined, an increase in population and agricultural 

expansion since the 1970s has resulted in a redistribution of 

some of the pumping stresses (Spechler and Kroening, 2007).

A hydrograph of the intermediate aquifer system 

ROMP 59 well also shows a continued steady recovery in 

water levels from the mid-1970s to 2007 (fig. 19C; location of well is shown in fig. 8). Water-level trends for the 

intermediate aquifer system, however, are not as dramatic as 

those observed in the Upper Floridan aquifer. The range of 

water-level fluctuations is about 8 to 10 ft for the less productive intermediate aquifer system, whereas the Upper Floridan 

aquifer has a much larger range, fluctuating as much as 40 ft 

between wet and dry seasons because of nearby pumpage. 

Based on statistical analysis, water levels in the intermediate 

aquifer system experienced a recovery of about 10 ft from the 

mid-1970s to 2007. This rise is likely the result of decreased 

pumpage from the Upper Floridan aquifer, which in turn 

causes reduced leakage from the intermediate aquifer system 

(Knochenmus, 2006). 

The cumulative groundwater withdrawals in the 

5,000-mi2 Southern West-Central Florida Groundwater Basin 

influence the groundwater levels in the upper Peace River 

basin because of the regional flow regime of the Upper 

Floridan aquifer. Water-level difference maps were created 

based on predevelopment minus the May 1975, May 2007, 

and September 2007 levels to evaluate the decline in groundwater levels across the regional Southern West-Central Florida 

Groundwater Basin and the localized upper Peace River basin. 

The May 1975 map was used, because groundwater pumpage 

for phosphate mining in the upper Peace River basin was 

at its highest level during this period. The 1975 difference 

maps of the regional groundwater basin show that the greatest 

declines (greater than 50 ft) occurred in the central and 

southwestern half of the upper Peace River basin and extended 

to Hillsborough, Manatee, and Hardee Counties (fig. 20A). 

The May 2007 difference map of the regional Southern 

West-Central Florida Groundwater Basin shows a rise in 

groundwater levels in the upper Peace River basin from the 

May 1975 levels. The lowest levels for the May 2007 difference map (greater than 50 ft) are located in Hillsborough, 

Manatee, and Hardee Counties (fig. 20B). Water-level difference maps for the upper Peace River basin for the current 

May and September 2007 levels (fig. 20C, D), indicate that 

the greatest declines are centered on the upper reaches of the 

Peace River near Bartow to Fort Meade (May 2007). The 

September 2007 difference map shows a water-level rise of 

about 10 to 20 ft from the May 2007 map near the Bartow to 

Fort Meade area.

The decline in the potentiometric surfaces of the Upper 

Floridan aquifer has affected the interactions between 

the Peace River and the underlying groundwater system. 

Figure 21 illustrates the level of the potentiometric surface 

of the Upper Floridan aquifer above the riverbed elevation when the area had flowing wells and springs. The area 

along the upper Peace River is now a recharge area where 
Streamflow 31

the potentiometric surface of the Upper Floridan aquifer is 

below the riverbed elevation, and river water flows downward 

through karst features to the underlying aquifers. During 

May 1975, when groundwater use for mining processes was 

at its highest level, the potentiometric surface of the Upper 

Floridan aquifer was as much as 50 ft below the riverbed 

elevation near Bartow (fig. 21). The May and September 

2007 conditions indicate a rise in aquifer water levels above 

the 1975 levels, but levels remain as much as 30 ft and 20 ft 

below the riverbed elevation, respectively (fig. 21). 

Streamflow 

Data collected at 10 USGS continuous gaging stations 

located along the upper Peace River and contributing tributaries 

(fig. 22) were used to (1) quantify flow under varying hydrologic 

conditions; (2) determine historical changes in flow; (3) quantify 

river flow losses and gains; (4) understand anomalies in flow 

conditions, such as reversals in flow, and (5) determine losses or 

gains from any unknown sources. There were five main-channel 

stations along the upper Peace River (fig. 22); Peace River at 

Bartow (site 1), Peace River near Bartow (site 7), Peace River at 

Clear Springs (site 11), Peace River near Homeland (site 16), and 

Peace River at Fort Meade (site 31). The inflow tributary gaging 

stations were Saddle Creek at Structure P-11 (site A), Peace Creek 

Drainage Canal near Wahneta (site B), and three phosphate-mine 

outfalls; Sixmile Creek (site 12), Phosphate Mine Outfall CS-8 

(site 14), and Barber Branch (site 15) (fig. 22). 

River Channel Characteristics Affecting Upper 

Peace River Flows

The upper Peace River was subdivided into four principal 

study reaches based on their unique hydrologic and karst 

characteristics (fig. 22). A physical description of the Peace 

River channel and associated tributaries and distributaries 

along Reaches 1 through 4 follows. 

Reach 1 begins at the Peace River at Bartow gaging 

station (site 1) at SR 60 and extends downstream 1.8 mi to 

the Peace River station near Bartow gaging station (site 7) 

(fig. 22). Saddle Creek (site A) and Peace Creek Drainage 

Canal (site B) drain the headwaters of the upper Peace River 

watershed, and inflows from these creeks largely determine 

the quantity of flow entering the upper part of Reach 1. The 

lower part of Saddle Creek drains Lake Hancock, and has been 

completely channelized from the lake outfall to its confluence 

with the Peace River and the Peace Creek Drainage Canal. 

A control structure (P-11) that regulates discharge from Lake 

Hancock is located about 2.3 mi upstream from the confluence of Peace Creek Drainage Canal and Saddle Creek. Peace 

Creek Drainage Canal also has been channelized in areas for 

flood control and, during higher flows, water from this canal 

moves into low-lying overbank areas. 

The effect of these altered streams has the largest impact 

on Peace River flows during low-flow conditions, when the 

tributary inflows are most needed to sustain flows in the river. 

For example, when the control structure at Saddle Creek is 

closed, backwater from the Peace Creek Drainage Canal can 

flow up into the altered low-gradient channel of Saddle Creek. 

Because of the large storage capacity of this 2.3-mi dredged 

channel, a substantial volume of water from the Peace Creek 

Drainage Canal is stored in the Saddle Creek channel when P-11 

is closed. As a result of channelization and increased storage, 

flows from these creeks to Reach 1 have been reduced during 

50

40

30

20

10

0

100

90

80

70

60

50

40

30

20

1900

100

90

80

70

ROMP 60 WELL

UPPER FLORIDAN AQUIFER

KISSENGEN SPRING

ROMP 59 WELL

INTERMEDIATE AQUIFER SYSTEM

DISCHARGE, IN CUBIC FEET

PER SECOND

WATER LEVEL, IN FEET

ABOVE NGVD OF 1929

EXPLANATION

Distance-weighted Least Squares fitting (McLain, 1974)

1920 1940 1960 1980 2000

WATER LEVEL, IN FEET ABOVE NGVD OF 1929

1900 1920 1940 1960 1980 2000

1900 1920 1940 1960 1980 2000

Estimated predevelopment levels 1975

(A)

(B)

(C)

Discharge

measurement

obtained in 1898

Figure 19. (A) Long-term discharge from Kissengen Spring, and 

long-term water levels in observation wells tapping the (B) Upper 

Floridan aquifer and (C) intermediate aquifer system (location 

of Kissengen Spring and wells are shown in figs. 13 and 8, 

respectively).
32 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Figure 20. Changes in the potentiometric surface of the Upper Floridan aquifer between predevelopment (modified from 

Johnston and others, 1980) and (A) May 1975 (modified from Mills and Laughlin, 1976) and (B) May 2007 levels (modified from 

Ortiz 2008a) for the Southern West-Central Florida Groundwater Basin, and between predevelopment and (C) May 2007 and 

(D) September 2007 levels (modified from Ortiz 2008b) for the Upper Peace River basin.

Bartow

Lakeland

Homeland

Lake Wales

Fort Meade

Winter Haven

82°00’ 81°45'

28°00’

27°45'

83° 82° 81°

28°

27°

EXPLANATION

Decrease in the potentiometric surface levels of the Upper Floridan aquifer

based on predevelopment levels, in feet (Johnston and others, 1980)

Greater than 50

40 to 50

30 to 40

20 to 30

10 to 20

0 to 10

POLK

SARASOTA

MANATEE

HILLSBOROUGH

HIGHLANDS

DE SOT0

HARDEE

CHARLOTTE

Upper

Peace

River

Basin

0 25 50 MILES

MAY

1975

Upper

Peace

River

Basin

MAY

2007

(A) (B)

(C) (D)

Lake

Hancock

Southern West-Central

Florida Groundwater

Basin

Peace River

GULF OF MEXICO

0 25 50 KILOMETERS

PASCO

OSCEOLA

GLADES

HENDRY

LEE

COLLIER

LAKE

PINELLAS

83° 82° 81°

28°

27°

POLK

SARASOTA

MANATEE

HILLSBOROUGH

HIGHLANDS

DE SOT0

HARDEE

CHARLOTTE

Upper

Peace

River

Basin

0 25 50 MILES

MAY

2007

Southern West-Central

Florida Groundwater

Basin

Peace River

GULF OF MEXICO

0 25 50 KILOMETERS

PASCO

OSCEOLA

GLADES

HENDRY

LEE

COLLIER

LAKE

PINELLAS

Peace

River

0 5 10 MILES

0 5 10 KILOMETERS

Bartow

Lakeland

Homeland

Lake Wales

Fort Meade

Winter Haven

82°00’ 81°45'

28°00’

27°45'

Upper

Peace

River

Basin

SEPTEMBER

2007

Lake

Hancock

Peace

River

0 5 10 MILES

0 5 10 KILOMETERS
Streamflow 33

low-flow conditions. Similar conditions have been observed at 

other Peace River tributary sites, where the flat, low-gradient 

ditches pond water rather than flow during low-flow conditions. 

Downstream from the confluence of these creeks, the 

Peace River channel along Reach 1 is characterized as sandy 

and gently meandering, and varies in width from about 30 to 

100 ft. This poorly incised channel transitions into a broad, 

heavily wooded high-water channel (floodplain) with banks 

rising from about one to several feet in height. The extent 

of areal inundation of the high-water channel is generally 

restricted to a floodplain corridor, bordered on both sides 

by elevated phosphate-mined landforms (Lewelling, 2003). 

Numerous cypress trees line the edges of the low-water 

channel and, at several locations, the exposed roots of longdecayed cypress trees are associated with observed cracks or 

openings that drain river water into the underlying aquifer. 

Karst features are located along this reach and have been 

observed to persistently drain river water to the underlying 

aquifers. Intermittent exposures of karstified limestone layers 

are present in the channel bed along the lowermost sections of 

the reach. During most low-flow conditions, flow is perennial 

along the upper section of Reach 1. The reach becomes dry 

only during prolonged droughts, such as in 2000-2002. 

Surface-water inflows into Reach 1 include two poorly 

incised drainage channels located on the eastern side of the 

Peace River floodplain and immediately downstream from 

the Peace River at Bartow station (site 1). These channels 

can drain to or receive water from a series of interconnected 

phosphate-mine pit lakes during high-flow conditions. During 

dry periods when flows in the Peace River at the Bartow 

station are about 50 cubic feet per second (ft3/s) or less, 

these channels typically do not convey any water between 

the pit lakes and the river. Two urban storm drainage ditches, 

one directly north and the other about 1,200 ft south of the 

Bartow WWTP, discharge flows into the Peace River. These 

ditches discharge to the Peace River only during intense 

storm events. 

Reach 2 begins at the Peace River near Bartow gaging 

station (site 7) and extends 1.9-mi downstream to the Peace 

River at Clear Springs gaging station (site 11) (fig. 22). Except 

for several limited areas of limestone outcrops, most of the 

channel bed is overlain by a thick layer of shifting sand. The 

Peace River consistently goes dry in Reach 2 during lowflow conditions because of a number of karst features in the 

channel that intercept and drain the surface-water flow. An 

approximate 1,700-ft-long section of channel at the lower end 

of Reach 2 generally remains ponded. The ponding in this 

section may indicate an impermeable sediment layer in the 

channel bed or a lack of karst features that can drain surfacewater flow. 

There are no tributaries, channels, or ditches contributing 

flow to the Peace River along Reach 2. The broad floodplain 

of the Peace River along this reach is almost entirely bordered 

by elevated phosphate clay-settling landforms that confine 

high-flow discharge within the floodplain boundaries. 

Located along Reach 2 are two distributary channels 

(Dover Sink Distributary and Gator Sink Distributary) that 

drain river water from the main channel under certain hydrologic conditions (fig. 22). The Dover Sink Distributary is an 

approximate 500-ft-long channel that winds through the floodplain and connects to Dover Sink. The poorly incised Gator 

Sink Distributary is about 200 ft upstream from the Peace 

River confluence with the Dover Sink Distributary. Gator Sink 

Distributary winds through the wooded floodplain and drops 

several feet in elevation before it reaches Gator Sink, which 

is about 800 ft west of the river. Also located in Reach 2 are 

two phosphate-mined pit lakes that accept backwater from the 

Peace River during high-flow conditions. 

Reach 3 begins at the Peace River at Clear Springs 

gaging station (site 11) and extends 3.9 mi downstream to 

the Peace River near Homeland gaging station on the SR 

640 bridge (site 16) (fig. 22). Reach 3 is defined by a poorly 

incised low-water channel, and this reach has not been 

observed dry during low-flow conditions. The extent of areal 

inundation of the high-water channel is generally restricted 

to the broad floodplain corridor, bordered on both sides by 

elevated reclaimed phosphate-mined landforms. 

0 2 4 6 8 10 12 14 16 18

220

ELEVATION, IN FEET ABOVE NGVD OF 1929

BARTOWPeace River

Lake Garfield

LAKE WALES

DISTANCE FROM WESTERN BOUNDARY OF THE

UPPER PEACE RIVER BASIN, IN MILES

20

A A’

200

150

100

50

20

EXPLANATION

GENERALIZED LAND SURFACE

POTENTIOMETRIC SURFACE PROFILE

UPPER FLORIDAN AQUIFER –Predevelopment levels (Modified

from Johnston and others, 1980)

UPPER FLORIDAN AQUIFER –SEPTEMBER, 2007 (Modified from

Ortiz, 2008b)

UPPER FLORIDAN AQUIFER –MAY 2007 (Modified from Ortiz,

2008a)

UPPER FLORIDAN AQUIFER –MAY 1975 (Modified from Mills

and Laughlin, 1976)

West East

Figure 21. Comparison of potentiometric-surface profiles of the 

Upper Floridan aquifer for predevelopment and recent conditions 

(location of section A-A’ is shown in fig. 8).
34 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Three phosphate-mine outfall gaging stations are 

located along Reach 3: Sixmile Creek (site 12), Phosphate 

Mine Outfall CS-8 (site 14), and Barber Branch (site 15; 

fig. 22). These outfalls generally supply water to Reach 3, 

except under extremely dry conditions. These three channels 

have been altered by strip mining for phosphate. The channels have been generally reclaimed as broad linear ditches. 

The contributing drainage areas for these channels are 

dominated by interconnected, reclaimed linear pit lakes and 

clay-settling areas, which are surrounded by various types of 

reclaimed landforms. 

Reach 4 begins near the Homeland gaging station (site 16) 

at the SR 640 bridge, and extends 5.4 mi downstream to the 

Peace River at Fort Meade gaging station (site 31) (fig. 22). 

The channel along Reach 4 is generally more incised than the 

upstream reaches and, during moderate-flow conditions, the 

0 1 2 3 MILES

0 1 2 3 KILOMETERS

Bartow

Homeland

Fort

Meade

Highland

City

1

2

98

60

28°00’

58’

56’

54’

52’

50’

48’

27°46’

81°54’ 52’ 50’ 48’ 81°46’

Lake

Hancock

Saddle Creek

Bear Branch

Kissengen

Spring (dry)

P

a

eace Creek Drain ge Canal

3

4

Peace

EXPLANATION

MINED AREA

HYDROLOGY ASSOCIATED WITH MINED AREAS

OPEN WATER

REACH AND REACH NUMBER

CLEAR SPRINGS MINE BOUNDARY

KISSENGEN SPRING—dry

LOCATION OF DISCHARGE MEASUREMENT SITES DURING

SEEPAGE RUNS AND NUMBER

KARST FEATURE

USGS STREAMFLOW GAGING STATION

1

60

17

630

555

640

98

98

17

17

559

Site

number

A

B

1

2

3

4

5

6

7

8

9

9a

10

11

12

13

14

15

16

17

18

19

20

26

29

30

31

River

mile

0

0.8

0.9

1.3

1.6

1.7

1.8

1.9

2.1

2.6

2.8

3.7

3.8

4.9

5.2

5.7

7.2

7.3

7.8

9.5

9.9

10.8

11.9

12.6

13.0

Location

Saddle Creek at Structure P-11 (gaging station)

Peace Creek Drainage Canal (gaging station)

Peace River at Bartow (gaging station)

Above Wabash Complex

Below Wabash Complex

Upper dragline crossing; Cook’s Ripple

Above Ledges; Fricano Fracture

Below Ledges

Peace River near Bartow (gaging station)

Below diffuse zone and Midway

Below Elephant Graveyard

Below Crevasses

Dover Sink and Dover Sink Distributary

Peace River at Clear Springs (gaging station)

Sixmile Creek (gaging station)

Above Kissengen Spring

Phosphate Mine Outfall (gaging station)

Barber Branch (gaging station)

Peace River near Homeland (gaging station)

Department of Environmental Protection ditch

Below Juvenile Detention Center

Mobil Outfall 3W Cut

Camp Meeting Branch

Below Mobil bridge

Rocky Branch

Sink Branch

Peace River at Fort Meade (gaging station)

1

CS-8

20

19

26

17

16

18

15

14

13

11

12

9a

10

9

8

4

5

6

7

3 2

1

29

30

31

Branch

Sink Branch

Phosphate Mine

Outfall CS-8

Tom’s Sink

Gator Sink and Distributary

B

A

Rocky

Sixmile

Creek

Otter Sink

Dover Sink and

Distributary

1

Pit

Lakes

Barber

Branch

1

Site 2 used as alternate discharge measurement section for site 1

during low-flow conditions

Base modified from U.S. Geological Survey digital data,

1:1000,000, 1985

Universal Transverse Mercator projection, zone 17

Figure 22. Locations of stream Reaches 1-4 and discharge measurement sites on the Peace River and tributaries during 

seepage runs.
Streamflow 35

reach can exhibit multiple braided channels in places. Most of 

the riverbed is sandy, except for limited areas of karst outcroppings and remnants of phosphate-mining pebbles. Inflows into 

Reach 4 are predominately from numerous reclaimed 

phosphate-mined channels and outfall structures associated 

with the clay-settling landforms that border much of the floodplain (high-water channel) corridor. Discharges from the largest 

reclaimed channels, Rocky Branch and Sink Branch, generally 

produce the largest inflows. Discharge at these outfalls was not 

monitored continuously, although periodic flow measurements 

were made on these tributaries.

Streamflow Conditions (2002-2007 Water Years)

Streamflow conditions for the upper Peace River during 

this investigation (2002-2007 water years) can be summarized as a period of extremes, and climatic conditions were a 

dominant control on these varying conditions. Rainfall deficits 

or excesses (measured from the long-term average rainfall of 

54.12 in.) were a major influence on streamflow in the study 

area, as shown in figure 23. Below-average streamflow conditions occurred during the 2002, 2006, and 2007 water years 

of greatest observed streamflow losses. The discharge hydrographs illustrate the change in flow over varying hydrologic 

conditions and streamflow losses, and also indicate overbank 

storage between Peace River gaging stations. Streamflow 

statistics for the upper Peace River and the tributary sites for 

the 2002-2007 water years are shown in table 1.

Prior to the beginning of this study, a severe drought 

affected most of Florida from 1998 to 2002 (Verdi and others, 

2006). During 2000 to 2002, the streamflow gage at the Peace 

River at Bartow (site 1) recorded periods of zero-flow for the 

first time in its 68-year history. Zero-flow periods occurred for 

37 days between May and June, 2000; 25 days between May 

and June, 2001; and 6 days in May 2002. Although another 

severe drought during the 2006-2007 water years caused 

below-average streamflow conditions in the study area, the 

Peace River at Bartow gaging station did not reach zero flow. 

During the study period (2002-2007 water years), the 

lowest annual mean discharge occurred during the 2007 water 

year, when a 2-year (2006-2007) cumulative rainfall deficit 

of almost 29 in. reduced streamflow in the upper Peace River 

(fig. 23). The annual mean discharge was only 18 ft3/s for 

the 2007 water year, which was the lowest annual discharge 

for the 68-year period of record at the Peace River at Bartow 

gaging station. Rainfall for the 2007 water year was 37 in. and 

was the third lowest in the 107 years of record, which accounts 

for the streamflow reductions in upper Peace River. Belowaverage conditions also existed in the 2002 and 2006 water 

years at this station, when the mean annual discharge was 110 

and 99 ft3/s, respectively. For comparison, the period of record 

mean discharge record at this station is 227 ft3/s. 

A trend analysis of long-term streamflow data from the 

Bartow gaging station shows a significant decline in streamflow during the 1940s, 1950s, and 1960s, and statistically 

unchanged streamflow during the 1970s (Hammett, 1990). 

Another trend analysis conducted for 1970s to 2003 data indicates that a decline in streamflow continues through this time 

period (Spechler and Kroening, 2007). Over time, declines 

in streamflow have been influenced by a number of factors 

attributed to (1) rainfall deficits that affect annual surface- and 

groundwater storage conditions, (2) surface-water inflows 

and baseflow declines, and (3) large groundwater withdrawals 

that have lowered the potentiometric surfaces of the intermediate aquifer system and Upper Floridan aquifer beneath the 

riverbed, which results in a loss of river water to karst features 

that drain to the underlying aquifers. 

During below-average streamflow years (2002, 2006, 

and 2007 water years), flow was observed draining into 

various karst features as flow in the channel progressed 

downstream from the Peace River at Bartow station (site 1, 

start of Reach 1). A comparison of discharge hydrographs 

between the upstream site (Peace River at Bartow; site 1) and 

the downstream site (Peace River near Bartow; site 7), mostly 

showed lower discharge at the downstream site (figs. 24-29). 

This difference reflects the loss of streamflow to the various 

sinks in this reach. This condition was most pronounced 

during periods when aquifer levels were low (figs. 24B-29B). 

-400

-300

-200

-100

0

100

200

300

400

2002

2003 2005

2006

2007

-40

-30

-20

-10

0

10

20

30

40

2004

DEPARTURE FROM AVERAGE RAINFALL,

IN INCHES

DEPARTURE FROM AVERAGE DISCHARGE,

IN CUBIC FEET PER SECOND

Departure from the average discharge of 227 cubic feet

per day (Peace River at Bartow)

Departure from the long-term average rainfall of 54.12

inches (Bartow National Weather Service station)

Figure 23. Departure from the average discharge and rainfall 

for the 2002-2007 water years.

when rainfall deficits occurred, and above-average streamflow 

conditions occurred during the 2003-2005 water years when 

rainfall excesses occurred. 

Discharge hydrographs for four streamflow sites on 

the Peace River and at the three mine outfall stations for 

the 2002-2007 water years are shown in figures 24 through 

29 (locations of stations are shown on fig. 22). Three mainchannel sites, from the Peace River at Bartow to the Peace 

River at Clear Springs gaging stations, are located in the area 
36 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

19.2

May June July August September

97.1

363

153

334

September 4, 2002

408

411 September 10, 2002

647

331

34.8 24.4

7.95

4.77

15.1

18.3

131 161

Peace River near Bartow gage

No flow recorded May 15-June 23

0.001

0.004

0.01

0.04

0.1

0.4

1

4

10

40

100

400

600

19.2

7.34 12.6

4.5

28.1

126 318

May 17, 2002

May 20, 2002

June 11, 2002

June 14, 2002

Peace River at Clear Springs gage

No flow recorded May 15-June 28

June 25, 2002

02294747 Sixmile Creek (Site 12)*

02294760 Barber Branch (Site 15)*

02294781 Peace River near Homeland (Site 16)

Discharge measurement (ft /s)

Rating discharge value

Seepage analysis date

3

22.0 37.3 48.0

Peace River at Clear Springs

No Flow recorded May 15-June 28, 2002

0.51

No Flow

8.03

3.84

238August 23, 2002

*(continuous discharge data not available

during the 2002 water year)

0.51

238

July

5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31

March April May June

No flow

No flow Peace River near Bartow

Peace River at Clear Springs

0.001

0.004

0.01

0.04

0.1

0.4

10

40

100

400

1,000

1,050

1

4

0.01

0.04

0.1

0.4

1

4

10

40

100

400

1,000

3,000

2002

DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND

Oct Nov Dec

2002

Jan Feb Mar Apr May Jun Jul Aug Sep

2001

(A) Reaches 1 and 2

Shaded area

expanded below

(B) Reaches 1 and 2

(C) Reach 3

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement (ft /s)

Seepage analysis date

3

Symbol and value color correspond with site line color

Minimum discharge (20 ft /s)

needed to maintain flow in

3 at Peace River at Bartow

Reaches 1 and 2, but not

necessarily past Dover Sink.

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement (ft /s)

Observation of no flow

Seepage analysis date

3

Symbol and value color correspond with site line color

34.8

Symbol and value color correspond with site line color

15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31 5 10 15 20 25 31 5 10 15 20 25 30

2002

Minimum discharge (20 ft /s)

needed to

maintain flow in

3

at

Peace River at Bartow

Reaches 1 and 2,

but not necessarily past Dover Sink.

Figure 24. Daily mean discharge for Reaches 1 and 2 for the (A) 2002 water year, (B) the 2002 low-flow period, and (C) daily 

mean discharge for Reach 3 for the partial 2002 water year.
Streamflow 37

Figure 25. Daily mean discharge for Reaches 1 and 2 for the (A) 2003 water year, (B) the 2003 low-flow period, and (C) daily 

mean discharge for Reach 3 for the 2003 water year.

94.5

183

72.7

82.9

94.5

58.5

8.69

19.4

26.5

77.9

64.6

April 23, 2003

April 25, 2003

209

183October 29, 2002

1,865

1,811January 7, 2003

2,200

201 268 148

2,048

497

769 870

187

666

226

July 9, 2003

707 630

217

153

646

September 23, 2003

164

May 13, 2003

0.93 0.72

1.26 1.06

188

158

17.2

897

4.86 7.74

2.52

2.18 1.92

10.6

0.24

0.01

4.90

2.10

37.0

131

95 72 51.8

42.9

24.8

11.7 5.90

80

May 13, 2003

0.01

0.04

0.1

0.4

1

4

10

40

100

400

1,000

3,000

1

2

5

10

20

50

100

200

300

209

1

2

5

10

20

50

100

200

500

1,000

2,000

3,000

2003

5 10 15 20 25 30

Minimum discharge (20 ft /s)

needed to

maintain flow in

3 at

Peace River at Bartow

Reaches 1 and 2,

but not necessarily past Dover Sink.

April May

DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND

Oct Nov Dec

2003

Jan Feb Mar Apr May Jun Jul Aug Sep

2002

(A) Reaches 1 and 2

Shaded area

expanded below

(B) Reaches 1 and 2

(C) Reach 3

Oct Nov Dec

2003

Jan Feb Mar Apr May Jun Jul Aug Sep

2002

Symbol and value color

correspond with

site line color

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement (ft /s)

Seepage analysis date

3

Rating discharge value

Symbol and value color correspond with site line color

Minimum discharge (20 ft /s)

needed to

maintain flow in

3 at

Peace River at Bartow

Reaches 1 and 2,

but not necessarily past Dover Sink.

02294747 Sixmile Creek (Site 12)

02294759 Phosphate Mine Outfall (Site 14)

02294760 Barber Branch (Site 15)

02294781 Peace River near Homeland (Site 16)

Discharge measurement (ft /s)

Seepage analysis date

3

CS-8

1.92

15 20 25 30 1

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement (ft /s)

Seepage analysis date

3

Symbol and value color correspond with site line color

201
38 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Figure 26. Daily mean discharge for Reaches 1 and 2 for the (A) 2004 water year, (B) the 2004 low-flow period, and (C) daily 

mean discharge for Reach 3 for the 2004 water year.

No Flow

2004

0.0001

0.001

0.01

0.1

1

10

100

600

63.1

25.2

30.1

9.70

4.40

47.8

86

39.3

8.44

14.3 10.9

4.36

38.1

3.98

37.4 68

18.0

March 9, 2004

April 27, 2004

June 1, 2004

May 19, 2004

June 29, 2004

80

57.4

46.2 November 6, 2003

330

142

145

30.9

152

114

3,600

433 634

25.4

22.8

609 August 19, 2004

201

1,540

2,7402,040

Hurricane Charley August 9, 2004

Hurricane Frances September 5, 2004

Hurricane Jeanne September 26, 2004

2,310

0.0001

0.001

0.01

0.1

1,000

6,000

1

10

100

0.01

0.1

1

10

100

1,000

4,000

36.1

22.2

62.0

4.60

23.7

12.3

13.2

April 27, 2004

1.29 1.61 3.06 2.21

1.49

3.80

64.6

1.52

35.3

794

3,270

August 19, 2004

4.57

22.4

216

1.93

0.77

0.59 November 6, 2003

1.20June 1, 2004

33.0

1.83

0.17

0.50

3.86

0.28

0.05

0.87

17.5

June 29, 2004

157

44

5.61

0.00001

0.00001 1 5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31

80

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement, cubic feet per second (ft /s)

Dotted line indicates transitional flow/no flow area

Rating discharge value

Observation of no flow

Seepage analysis date

3

Minimum discharge (20 ft /s)

needed to

maintain flow in

3 at

Peace River at Bartow

Reaches 1 and 2,

but not necessarily past Dover Sink.

April May June July

DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND

Oct Nov Dec

2004

Jan Feb Mar Apr May Jun Jul Aug Sep

2003

(A) Reaches 1 and 2

Shaded area

expanded below

(B) Reaches 1 and 2

(C) Reach 3

Oct Nov Dec

2004

Jan Feb Mar Apr May Jun Jul Aug Sep

2003

Symbol and value color correspond with site line color

22.8

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement (ft /s)

Seepage analysis date

Dotted line indicates transitional flow/no flow area 3

Symbol and value color correspond with site line color

March

490

Minimum discharge (20 ft /s)

needed to

maintain flow in

3 at

Peace River at Bartow

Reaches 1 and 2,

but not necessarily past Dover Sink.

1.20

02294747 Sixmile Creek (Site 12)

02294759 Phosphate Mine Outfall (Site 14)

02294760 Barber Branch (Site 15)

02294781 Peace River near Homeland (Site 16)

36.1Discharge measurement, cubic feet per second (ft /s) CS-8

Rating discharge value

Observation of no flow

Seepage analysis date

3

Symbol and value color correspond with site line color
Streamflow 39

Figure 27. Daily mean discharge for Reaches 1 and 2 for the (A) 2005 water year, (B) a high-flow period during 2005, and (C) daily 

mean discharge for Reach 3 for the 2005 water year.

7.1

10

20

50

100

200

500

1,000

2,000

5,000

6,000

265 248 December 7, 2004

243

412

438 March 31, 2005

342

1,520

1,392

1,930

218 192

225

109

848 1,136

546

490

547

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

100

200

500

1,000

2,000

4,000

March 31, 2005

617

1,510

167

622

51.0

3.78

45.4

7.1

8.23

1.73 1.78

52.3

16.0 16.6

8.00

19.1

Missing Data

10

20

50

100

200

500

1000

2000

3000

848

1,136

547 490

546

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement, cubic feet per second (ft /s) 3

490

109

342

1 5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31 5 10 15 20 25 31 5 10 15 20 25 30

6.32

02294747 Sixmile Creek

02294759 Phosphate Mine Outfall

02294760 Barber Branch

02294781 Peace River near Homeland

Discharge measurement (ft /s)

Rating discharge value

Seepage analysis date

3

CS-8

2005

May June July August September

DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND

Oct Nov Dec

2005

Jan Feb Mar Apr May Jun Jul Aug Sep

2004

(A) Reaches 1 and 2

Shaded area

expanded below

(B) Reaches 1 and 2

(C) Reach 3

Oct Nov Dec

2005

Jan Feb Mar Apr May Jun Jul Aug Sep

2004

Symbol and value color correspond with site line color

Symbol and value color correspond

with site line color

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement (ft /s)

Seepage analysis date

3

Rating discharge value

Symbol and value color correspond

with site line color
40 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Figure 28. Daily mean discharge for Reaches 1 and 2 for the (A) 2006 water year, (B) the 2006 low-flow period, and (C) daily mean 

discharge for Reach 3 for the 2006 water year.

220

6.32

02294747 Sixmile Creek

02294759 Phosphate Mine Outfall

02294760 Barber Branch

02294781 Peace River near Homeland

CS-8

Discharge measurement (ft /s)

Seepage analysis date

3

January 24, 2006

6.32

14.6

234

7.21

9.90

10.9

2.99

1.18

58.6 74.6

10.6

6.51

90.4

4.72

3.32 3.05

0.106

0.146 0.123

2.67

1.93

5.93

6.23

January 24, 2006

51.9

41.0

52.6

231

220

185

45.5

65.9

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement (ft /s)

Seepage analysis date

Dotted line indicates area of possible no flow 3

0.01

0.02

0.05

0.1

0.5

1

2

5

10

20

50

1,000

100

200

500

0.2

63.0

50.1 28.0

13.8

11.0

61.2

22.7

8.73

4.62

15.8

March 2, 2006

March 13, 2006

March 30, 2006

April 11, 2006

May 30, 2006

June 23, 2006

June 8, 2006

6.12

18.5

17.1 11.3 12.0

4.50

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Dotted line indicates area of possible no flow

4.13

4.50

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

100

200

300

2006 July

5 15 31 2010 25 5 15 30 2010 25 5 15 31 2010 25 5 15 30 2010 25 5 15 31 2010 25 5 15 2010 25 31

March April May June August

Discharge measurement (ft /s)

Rating discharge value

Observation of no flow

Seepage analysis date

3

DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND

0.01

0.04

0.1

0.4

1

4

10

40

100

400

1,000

Tropical Storm Alberto

June 12, 2006

Symbol and value color correspond with site line color

Oct Nov Dec

2006

Jan Feb Mar Apr May Jun Jul Aug Sep

2005

Minimum discharge (20 ft /s)

needed to maintain flow in

3

at Peace River at Bartow

Reaches 1 and 2, but not

necessarily past Dover Sink.

(A) Reaches 1 and 2

Shaded area

expanded below

(B) Reaches 1 and 2

Minimum discharge (20 ft /s)

needed to maintain flow in

3 at Peace River at Bartow

Reaches 1 and 2, but not

necessarily past Dover Sink.

(C) Reach 3

Oct Nov Dec

2006

Jan Feb Mar Apr May Jun Jul Aug Sep

2005

Symbol and value color correspond with site line color

Symbol and value color correspond

with site line color
Streamflow 41

Figure 29. Daily mean discharge for Reaches 1 and 2 for the (A) 2007 water year, (B) the 2007 low-flow period, and (C) daily mean 

discharge for Reach 3 for the 2007 water year. 

2.20

May 11, 2007

May 15, 2007

7.37

e

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (Site 11)

Discharge measurement (ft /s) 3 4.13

Symbol and value color correspond with site line color

17

Discharge measurement (ft /s)

Observation of no flow

Rating discharge value

3

Seepage analysis date

0.001

0.004

0.01

0.04

0.1

0.4

1

4

10

40

100

02294747 Sixmile Creek

02294759 Phosphate Mine Outfall

02294760 Barber Branch

02294781 Peace River near Homeland

CS-8

November 15, 2006

Missing data

27.6

3.66

61.6

3.74

1.22

1.55

3.79

9.54

4.67

4.08

2.73

1.34

10.7 13.7

7.38

4.83 4.37

0.219

1.43

1.34

0.010

2.52 2.20 1.65

DISCHARGE, IN CUBIC FEET PER SECOND

0.001

0.004

0.01

0.04

0.1

1

4

10

40

0.4

100

150

Oct Nov Dec

2007

Jan Feb Mar Apr May Jun Jul Aug Sep

2006

Minimum discharge (20 ft /s) needed to

maintain flow in

3 at Peace River at Bartow

Reaches 1 and 2, but not necessarily past Dover Sink.

October 11, 2006

November 14, 2006

February 8, 2007

March 23, 2007

July 18, 2007

August 29, 2007

58.8

31.5

22.5

34

9.64 6.05

4.13

24.7 14.2

49 46.4 37.1

6.67

20.6

4.29

15.5

5.19

7.91

17

Figure 29. Daily mean discharge for Reaches 1 and 2 for (A) the 2007 water year, (B) the 2007 low-flow period, and (C) daily

mean discharge for Reach 3 for the 2007 water year.

(A) Reaches 1 and 2

Shaded area

expanded below

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

30

02294650 Peace River at Bartow (Site 1)

02294655 Peace River near Bartow (Site 7)

02294775 Peace River at Clear Springs (site 11)

Discharge measurement (ft /s) 3

0.10e

1.45

7.37

June 13, 2007

4.18

8.11

2.36

April

3 6 9 12 15 18 21 24 27 30

May June

0.01 3 6 9 12 15 18 21 24 27 30 3 6 9 12 15 18 21 24 27 30

2007

Observation of no flow

Rating discharge value

Seepage analysis date

(B) Reaches 1 and 2

Minimum discharge (20 ft /s)

needed to maintain flow in

3 at Peace River at Bartow

Reaches 1 and 2, but not

necessarily past Dover Sink.

DISCHARGE, IN CUBIC FEET PER SECOND

1 1

DISCHARGE, IN CUBIC FEET PER SECOND

(C) Reach 3

Symbol and value color correspond

with site line color

Oct Nov Dec

2007

Jan Feb Mar Apr May Jun Jul Aug Sep

2006

Symbol and value color correspond

with site line color

Estimated discharge

Observation of no flow

Seepage analysis date
42 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Table 1. Streamflow statistics for the upper Peace River and tributaries for the 2002-2007 water years.

[Streamflow statistics based on computed discharge from rating curves. ft3/s, cubic feet per second; e, estimated; –, missing or no data; *first zero flow day in year]

Sites

(fig. 22) Station Water 

year

Annual 

mean

discharge

(ft3

/s)

Maximum daily mean 

discharge

Minimum daily mean 

discharge

Number

of

 zero 

flow 

days

Number 

of

 days

of 

 (ft record 3

/s) Date (ft3/s) Date

Site A Saddle Creek at Structure P-11

Station number: 02294491

Period of record: 44 years

December 1963-September 2007

Period of record mean discharge: 65 ft3/s

Mean discharge for May 2002-

September 2007: 101 ft3/s

2002 50 604 09-13-2002 0.00 01-03-2002* 183 365

2003 190 936 01-04-2003 5.7 06-03-2003 0 365

2004 131 1,620 09-11-2004 0.00 06-13-2004* 14 365

2005 155 1,310 10-01-2004 0.00 02-18-2005* 9 365

2006 23 238 11-04-2005 0.03 05-30-2006 0 365

2007 0.46 28 06-17-2007 0.00 08-11-2007* 25 365

Site B Peace Creek Drainage Canal

Station number: 02293987

Period of record: 16 years

March 1991-September 2007

Period of record mean discharge: 101 ft3/s

Mean discharge for May 2002-

September 2007: 132 ft3/s

2002 51 283 10-01-2001 0.81 05-14-2002 0 365

2003 202 705 01-03-2003 12 10-22-2002 0 365

2004 113 977 09-10-2004 3.3 06-03-2004 0 365

2005 288 892 10-01-2004 36 02-19-2005 0 365

2006 63 528 10-26-2005 1.7 06-10-2006 0 365

2007 15 73 02-03-2007 3.1 05-14-2007 0 365

Site 1 Peace River at Bartow 

Station number: 02294650

Period of record: 68 years

October 1939-September 2007

Period of record mean discharge: 227 ft3/s

Mean discharge for May 2002-

September 2007: 292 ft3/s

2002 110 881e 09-14-2002 0.00 05-13-2002* 6 365

2003 483 2,240 01-05-2003 21 05-17-2003 0 365

2004 344 4,010 09-11-2004 2.9 06-04-2004 0 366

2005 545 3,520 10-01-2004 83 02-25-2005 0 365

2006 99 693 10-28-2005 1.8 06-10-2006 0 365

2007 18 62 10-01-2006 0.41 05-15-2007 0 365

Site 7 Peace River near Bartow 

Station number: 02294655

Period of record: 5.38 years

Mean discharge for May 2002-

September 2007: 287 ft3/s

2002 – 820 09-15-2002 0.00 05-15-2002* 39 139

2003 492 1,890 01-05-2003 14 05-17-2003 0 365

2004 324 4,090 09-12-2004 0.00 05-27-2004* 14 365

2005 545 3,530 10-01-2004 69 02-25-2005 0 365

2006 97 563 10-29-2005 0.23 06-06-2006 0 365

2007 12 115 10-01-2006 0.00 04-04-2007* 82 365

Site 11 Peace River at Clear Springs 

Station number: 02294775

Period of record: 5.38 years

May 2002-September 2007

Mean discharge for May 2002-

September 2007: 263 ft3/s

2002 – 643 09-15-2001 0.00 05-15-2002* 45 139

2003 444 1,850 01-06-2003 2.6 05-18-2003 0 365

2004 264 2,950 09-12-2004 0.85 06-01-2004 0 365

2005 545 2,870 10-01-2004 62 02-25-2005 0 365

2006 92 661 10-29-2005 0.00 03-17-2006* 119 365

2007 5 74 10-01-2006 0.00 10-23-2006* 175 365

Site 16 Peace River near Homeland

Station number 02294781

Period of Record: 5.38 years

May 2002-September 2007

Mean discharge for May 2002-

September 2007: 298 ft3/s

2002 112 893 09-16-2002 0.00 05-26-2002* 4 365

2003 503 2,380 01-06-2003 4.2 05-18-2003 0 365

2004 304 3,400 09-13-2004 1.6 06-01-2004 0 365

2005 599 3,360 10-01-2004 73 02-25-2005 0 365

2006 103 771 10-29-2005 0.73 05-15-2006 0 365

2007 11 65 10-01-2006 0.00 05-31-2007* 14 365

Site 31 Peace River at Fort Meade 

Station number: 02294898

Period of record: 33.3 years

June 1974-September 2007

Mean discharge for May 2002-

September 2007: 343 ft3/s

2002 132 973 09-25-2002 0.19 05-18-2002 0 365

2003 584 2,040 01-06-2003 8.8 05-18-2003 0 365

2004 327 2,450 09-13-2004 4.2 06-07-2004 0 365

2005 695 2,390 10-01-2004 43 02-24-2005 0 365

2006 119 850 10-30-2005 1.7 05-08-2006 0 365

2007 22 134 02-03-2007 0.01 06-01-2007 0 365
Streamflow 43

Sites

(fig. 22) Station Water 

year

Annual 

mean

discharge

(ft3

/s)

Maximum daily mean 

discharge

Minimum daily mean 

discharge

Number

of

 zero 

flow 

days

Number 

of

 days

of 

 (ft record 3

/s) Date (ft3/s) Date

Site 12 Sixmile Creek 

Station number: 02294747

Period of record: 4.83 years

Mean discharge for December 2002-

September 2007: 28 ft3/s

2002 – – – – – –

2003 – 181 01-04-2003 3.4 04-25-2003 0 304

2004 42 346 09-10-2004 1.7 03-27-2004 0 365

2005 40 267 10-01-2004 1.3 04-26-2005 0 365

2006 11 107 10-27-2005 0.00 05-04-2006* 14 365

2007 4 25 02-07-2007 0.00 05-29-2007* 16 365

Site 14 Phosphate Mine Outfall CS-8

Station number: 02294759

Period of record: 3.17 years

Mean discharge for February 2003-

May 2005 and November 2006-

September 2007: 5.2 ft3

/s

2002 – – – – – –

2003 – 60 08-26-2003 0.01 05-15-2003 0 242

2004 6 82 09-12-2004 0.00 04-10-2004* 23 365

2005 – 79 10-01-2004 e0.17 04-23-2005 0 229

2006 – – – – – –

2007 – 19 07-23-2007 0.00 03-28-2007* 39 320

Site 15 Barber Branch 

Station number: 02294760

Period of record: 4.83 years

Mean discharge for December 2002-

September 2007: 13.2 ft3/s

2002 – – – – – –

2003 – 114 01-01-2003 0.00 06-17-2003* 5 304

2004 20 253 09-12-2004 0.37 12-26-2003 0 365

2005 25 250 10-01-2004 1.3 04-17-2005 0 365

2006 8 66 10-24-2005 1.8 08-22-2006 0 365

2007 1 13 04-08-2007 0.03 05-31-2007 0 365

Table 1. Streamflow statistics for the upper Peace River and tributaries for the 2002-2007 water years—Continued

[Streamflow statistics based on computed discharge from rating curves. ft3/s, cubic feet per second; e, estimated; –, missing or no data]

During this study, the Peace River near Bartow station (site 7) 

had more zero-flow days than the upstream Peace River at 

Bartow (site 1), with 39 zero-flow days out of the 139 total 

recorded days in 2002 (May 15 to September 30), 14 days in 

2004, and 82 days in 2007 (table 1). In most cases, the zeroflow days recorded at the Peace River near Bartow (site 7) 

indicated that the flow in Reach 1 terminated at a large sink 

(Ledges Sink), located about 700 ft upstream from the gaging 

station. 

Streamflow losses also occurred downstream from Peace 

River near Bartow gaging station (site 7) as flow progressed 

into Reach 2. A comparison of streamflow hydrographs 

between the upstream Peace River near Bartow station (site 7) 

with the downstream Peace River at Clear Springs gaging 

station (site 11) indicated that discharge at the downstream 

site was reduced or absent, reflecting the loss of water through 

the karst features in Reach 2 (figs. 24B-29B). Zero-flow days 

were reported at the Peace River at Clear Springs (site 11) 

for 45 days in 2002, 119 days in 2006, and 175 days in 2007 

(table 1).

During below-average streamflow and groundwater 

conditions, and when the discharge at the Peace River at 

Bartow (site 1) was about 20 ft3/s or less, all of the flow in 

the river drained into various karst features in the channel and 

flow usually ended within Reach 2 (Dover Sink) (figs. 24B, 

26B, 28B, and 29B). During the 2006-2007 water years, the 

number of zero-flow days progressively increased, indicating 

a decline in floodplain storage along the upper Peace River. 

During these low-flow conditions, streamflow losses to the 

various karst features in the upper two reaches either reduced 

or eliminated the Peace River flow contributions into Reach 3.

During the 2006-2007 water years, the Peace Creek 

Drainage Canal (site B, fig. 22) supplied the largest amount of 

tributary flow to the upper Peace River. The mean discharge 

for the Peace Creek Drainage Canal for those years was 63 

and 15 ft3/s, respectively, compared to the period of record 

mean discharge of 101 ft3/s (table 1). The mean discharge for 

Saddle Creek (site A, fig. 22) during the 2006-2007 water 

years was 23 and 0.46 ft3/s, respectively, compared to the 

period of record mean discharge of 65 ft3/s (table 1). Saddle 

Creek had a number of zero-flow days during the study period 

(2002, 2004, 2005, and 2007; table 1) which were often the 

result of closing the gate at the P-11 Structure.

Of the three phosphate mine outfalls sites, Sixmile Creek 

(site 12) supplied the most flow to Reach 3. But during the 

below-average 2006-2007 water years, Sixmile Creek supplied 

only 11 and 4 ft3/s of mean discharge, respectively, compared 

to the period of record mean discharge of 28 ft3/s (table 1). 

During the 2006-2007 water years, Sixmile Creek and 

Phosphate Mine Outfall CS-8 also had a number of zero-flow 
44 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

days (table 1). Discharge hydrographs for the three outfall 

tributaries and the Peace River near Homeland (site 16) are 

shown in figures 25C-29C. Hydrographs of the phosphatemine outfalls illustrate the limited amount of inflow to the 

upper Peace River during low-flow conditions (figs. 28C 

and 29C). Discharge hydrographs for these sites indicate 

that the flows were “flashy” and that discharge receded 

rapidly after peak discharge events. 

For the study period, streamflow was greatest during 

the 2003-2005 water years, when above-average precipitation fell in the study area. Most of the excess rainfall 

was during the 2003 water year when there was an 

increase of 29 in. above the long-term average (54 in.) 

rainfall (fig. 23). In addition to excess rain in 2003, 

three hurricanes crossed over the upper Peace River 

basin during a 6-week period from August through 

September 2004, producing about 24 in. of rain in the 

basin. The combined effects of two of these hurricanes resulted in the second greatest discharge for the 

period of record at Peace River at Bartow (4,010 ft3/s) 

on September 11, 2004 (table 1). These storms 

caused considerable flooding, and high-to-medium 

streamflow persisted into the following 2005 water 

year. The greatest annual mean discharge (545 ft3/s) 

for the study period occurred during the 2005 water 

year, which is more than double the long-term mean 

discharge (227 ft3/s) (table 1). During the 2005 water 

year, Saddle Creek and Peace Creek Drainage Canal 

supplied a substantial amount of flow to the upper 

Peace River, with the annual mean discharges of 155 

and 288 ft3/s, respectively.

During high-flow periods, a large loss in flow was 

observed between the upstream and downstream gaging 

stations between Reaches 1 and 2 of the upper Peace River. 

This large volume loss between stations was typically 

the result of floodplain storage rather than losses to karst 

features. The upper Peace River channel is poorly incised 

along much of Reaches 1-2, and the transition of flow from 

the low-water to high-water channel generally occurs at 

a discharge of about 100 ft3/s at Peace River at Bartow 

(site 1). The land-surface elevation contours of 88, 90, 92, 

and 94 ft above NGVD 1929 (shown in (figs. 30A-D) reflect 

potentially inundated areas along the upper Peace River 

with increasing river-stage levels. The river-stage levels 

for Peace River at Bartow, Peace River near Bartow, and 

Peace River at Clear Springs for the study period are shown 

in figure 31, as well as the respective river level ranges for 

when the Peace River is in the main channel.

 In Reach 1, when river levels were greater than about 

91.50 ft above NGVD 1929 at Peace River at Bartow, water 

drained into a series of interconnected pit lakes by way of a 

pair of small ditches along the eastern floodplain (fig. 30). 

At higher river stages in Reach 2 (greater than 91.0 ft above

NGVD 1929) large storage losses occurred as river water 

drained into pit lakes along the western floodplain. The small 

size of the upper pit lake (about 14 ac) limits the amount of 

water that can be stored, whereas the much larger lower pit 

lake (about 40 ac) has the capacity to store large volumes of 

river backwater (fig. 30). The backwater conditions to the pit 

lakes occurred during extreme high-water conditions in 2003, 

2004, and 2005 (fig. 31). 

Discharge-Duration Hydrographs and Curves

Daily discharge-duration hydrographs for the Peace River 

at Bartow gaging station for the 68 years of record (1940-

2007 water years) are shown in figure 32. The 90th to 100th

percentile (maximum discharge) reflect very wet conditions, 

the 25th to 75th percentiles indicate normal conditions, and the 

10th to 0th percentiles (minimum discharge) indicate very dry 

conditions. The minimum, maximum, average, and median 
Streamflow 45

discharge values for the 0th

through 100th percentiles 

are shown in figure 32. The 

discharge-duration hydrographs 

indicate that the greatest flows 

generally occur during the 

rainy season in June, September, and October (fig. 32). 

In addition, notable high flows occur in March. The 

lowest flows occur at the end of the dry season from 

May into June. The 0th percentiles (zero flow periods) 

for the 68 years of record occurred during May and 

June of 2000-2002.

 The annual (2002-2007) discharge-duration curves 

obtained at the Peace River at Bartow station and their 

relations to the long-term 68-year discharge-duration curve 

indicate that the 2002, 2006, and 2007 water years were 

below the long-term duration curve throughout most of 

the range of hydrologic conditions (figs. 33A, E, and F). 

Discharge-duration curves for the 2003 and 2005 water years 

at the Peace River at Bartow station indicate relatively high, 

stable discharge throughout most of the range of flows and 

suggest that most of the water may have been derived from 

floodplain storage (figs. 33B and D). Duration curves for the 

2004 water year at the Peace River at Bartow station show a 

mixed ranged of hydrologic conditions (fig. 33C). The relatively flat slope of the duration curve during 2007 water year 

indicates persistent and steady low flow that was confined 

to the low-water channel (fig. 33F). The steep slope and 

abrupt ending at the low end of the duration curves indicates 

streamflow declines and periods of no flow. 

A comparison of duration curves for the three gaging 

stations along Reaches 1 and 2 (sites 1, 7, and 11; fig. 22) 

shows streamflow gains, losses, or constant discharge 

conditions for the 2003-2007 water years (fig. 33B-F). 

Duration curves for the 2004 water year show a mix of 

hydrologic conditions, with flow losses and gains between 

gaging stations. For the 2003 and 2005 water years, the 

three gaging stations showed constant discharge conditions 

for most of the water year, except at the low end of the 

duration curve. Duration curves for the 2006-2007 water 

years illustrate flow losses between sites, with flow losses in 

Reach 1 not as extensive as in Reach 2 (figs. 33E-F).

Low water levels hinder feasibility of canoeing and maintenance of 

healthy ecosystems. Note high water-level marks on trees located 

downstream of Peace River at Wabash (site 2). High water-level 

marks are the result of high flows during the 2005 water year. 

Photo credit: P.A. Metz, USGS
46 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

81°49’ 81°48

27°54’

27°53’

27°52’

88 feet

Peace

River

1 MILE

(A)

Peace River at Bartow

Peace River near Bartow

Peace River at Clear Springs

EXPLANATION

GAGING STATION

81°49’ 81°48

27°54’

27°53’

27°52’

90 feet

Peace

River

(B)

Peace River at Bartow

Peace River

near Bartow

Peace River at

Clear Springs

81°49’ 81°48

27°54’

27°53’

27°52’

92 feet

Peace

River

(C)

Peace River at Bartow

Peace River at Clear Springs

81°49’ 81°48

27°54’

27°53’

27°52’

94 feet

Peace

River

(D)

Peace River

at Bartow

Peace River

near Bartow

Peace River at Clear Springs

Peace River

near Bartow

ELEVATION CONTOUR—

in feet above NGVD 1929

0

0 1 KILOMETER

Pit Lakes

Pit Lakes

Pit Lakes

Pit Lakes

Pit Lakes

Pit Lakes

Pit Lakes

Pit Lakes

Pit Lakes

Pit Lakes

Pit Lakes

Pit Lakes

Figure 30. Land-surface elevation contours along the upper Peace River at (A) 88 feet, (B) 90 feet, (C) 92 feet, and (D) 94 feet 

above NGVD 1929.
Streamflow 47

2002 2003 2004 2005 2006 2007

Peace River at Bartow

Peace near Bartow

Peace at Clear Springs

River

River

WATER LEVEL, IN FEET ABOVE NGVD 1929

EXPLANATION

100

98

96

94

92

90

88

86

84

Range of elevations for which Peace River at Bartow is in the main

channel

Range of elevations for which Peace River near Bartow and Peace River

at Clear Springs are in the main channel

WATER YEAR

Figure 31. Approximate range of 

water-level elevations for which 

the upper Peace River is within 

the main channel.

Figure 32. Daily flow-duration hydrographs for Peace River at Bartow, water years 1940 through 2007.

10,000

1,000

100

10

1

0.1

0.01

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

Maximum

90th percentile

75th percentile

50th percentile

25th percentile

10th percentile

Minimum

DISCHARGE, IN CUBIC FEET PER SECOND

Statistics based on data collected for water years 1940-2007.

PEACE RIVER AT BARTOW

Range Mimimum Maximum Average Median

Percent range in daily streamflow, in cubic feet per second

Maximum

Minimum

90th percentile

75th percentile

50th percentile

25th percentile

10th percentile

427

177

67

25

11

5

0

4400

1497

692

335

164

74

24

1545

572

293

123

52

23

7

1389

501

239

98

37

19

6
48 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

10,000

1,000

100

10

1

0.1

0.01

0 10 20 30 40 50 60 70 80 90 100

10,000

1,000

100

10

1

0.1

0.01

0 10 20 30 40 50 60 70 80 90 100

Peace River at Bartow ( ) 2002

110 ft /s annual 3

site 1

mean discharge

Peace River at Bartow (site 1) 1940-2007

227 ft /s long-term mean discharge 3

DISCHARGE, IN CUBIC FEET PER SECOND

(A) 2002 Water Year

Peace River at Bartow ( ) site 1

483 ft /s annual mean discharge 3

Peace River at Bartow ( ) 1940-2007 site 1

227 ft /s long-term mean discharge 3

Peace River at Clear Springs ( )site 11

444 ft /s annual mean discharge 3

Peace River near Bartow ( )site 7

492 ft /s annual mean discharge 3

Peace River at Bartow ( ) 2004

344 ft /s annual 3

site 1

mean discharge

Peace River at Bartow ( ) 1940-2007

227 ft /s long-term 3

site 1

mean discharge

Peace River at Clear Springs ( )

264 ft /s annual mean discharge 3

site 11

Peace River near Bartow ( )

324 ft /s annual 3

site 7

mean discharge

Peace River at Bartow ( ) 2005

545 ft /s annual mean discharge 3

site 1

Peace River at Bartow ( ) 1940-2007

227 ft /s long-term mean discharge 3

site 1

Peace River near Bartow ( )

545 ft /s annual 3

site 7

mean discharge

Peace River at Clear Springs ( )

545 ft /s annual 3

site 11

mean discharge

Peace River at Bartow ( ) 2006site 1

99 ft /s annual mean discharge 3

Peace River at Bartow ( ) 1940-2007 site 1

227 ft /s long-term mean discharge 3

Peace River at Clear Springs ( )site 11

92 ft /s annual mean discharge 3

Peace River near Bartow (site 7)

97 ft /s annual mean discharge 3

119 days of no flow

PERCENTAGE OF TIME DISCHARGE WAS EQUALED OR EXCEEDED

Peace River at Bartow ( ) 2007site 1

18 ft /s annual mean discharge 3

Peace River at Bartow ( ) 1940-2007 site 1

227 ft /s long-term mean discharge 3

Peace River near

Bartow ( )site 7

12 ft /s annual mean discharge 3

240 days of

no flow

80 days of

no flow

Peace River at

Clear Springs ( )site 11

5 ft /s annual mean discharge 3

Data not available for Peace River near Bartow and

Peace River at Clear Springs for the 2002 water year

(B) 2003 Water Year

10,000

1,000

100

10

1

0.1

0.01

0 10 20 30 40 50 60 70 80 90 100

10,000

1,000

100

10

1

0.1

0.01

0 10 20 30 40 50 60 70 80 90 100

(C) 2004 Water Year (D) 2005 Water Year

10,000

1,000

100

10

1

0.1

0.01

0 10 20 30 40 50 60 70 80 90 100

10,000

1,000

100

10

1

0.1

0.01

0 10 20 30 40 50 60 70 80 90 100

(E) 2006 Water Year (F) 2007 Water Year

Figure 33. Discharge-duration curves for the Peace River at Bartow, Peace River near Bartow, and Peace River at Clear 

Springs gaging stations for the (A) 2002, (B) 2003, (C) 2004, (D) 2005, (E) 2006, and (F ) 2007 water years, with a long-term 

comparative curve for the Peace River at Bartow gaging station for the 1940-2007 water years.
Streamflow 49

Effects of Karst Development on 

Streamflow Losses 

The area along the upper Peace River is characterized 

as a carbonate karst terrain that has distinctive karst features 

and a hydrology defined by the combination of high rock 

solubility and well-developed secondary porosity (Ryder, 

1985). A number of prominent karst features are located along 

the upper Peace River in the high-water floodplain and along 

the existing low-water channel. Depending on Peace River 

stage and groundwater conditions, these karst features can act 

as conduits for flow to the underlying aquifers. Seepage runs, 

in conjunction with monitoring of aquifer levels, were used to 

describe the timing, volume of water exchanged, and effects 

of karst development on streamflow losses along the upper 

Peace River. 

Seepage Investigations

Seepage runs were conducted to determine where the 

greatest streamflow losses occurred along the upper Peace 

River from Bartow to Fort Meade (Reaches 1-4; fig. 22). 

Streamflow gains and losses, in cubic feet per second, along 

the Peace River were calculated using the following equation:

Qs = Qd - Qu - Qt, (1)

where

Qs = gain (positive) or loss (negative) in streamflow 

between adjacent sites;

Qd = streamflow at downstream site;

Qu = streamflow at upstream site; and

Qt = total streamflow for all tributaries between 

upstream and downstream sites.

Seepage runs were performed during baseflow conditions, 

when rainfall was at a minimum and most streamflow was 

derived from groundwater seepage, rather than from runoff. 

During these seepage runs, a net increase in stream discharge 

along the reach was interpreted as a gain in groundwater 

discharge into the river. Conversely, a net reduction along 

the reach was a loss of river water into the aquifers. If stream 

discharge remained constant along a particular reach, then 

the river neither gained water from, nor lost water to, the 

underlying aquifers. Figures 34 and 35 show the losses and 

gains during seepage investigations along Reaches 1-4 and 

Reaches 1 and 2, respectively. Table 2 indicates the computed 

and measured discharge at selected sites and total streamflow 

losses along Reaches 1 and 2 during below-average flow 

conditions.

During this investigation, two seepage runs (May 13-14, 

2003, and January 24, 2006) were conducted along Reaches 

1-4 from Peace River at Bartow station (site 1) to Peace River 

at Fort Meade station (site 31) (fig. 22). In addition, results 

of a previous seepage run (May 28-29, 1996) conducted 

along Reaches 1-4 were used for comparison to the current 

seepage results. 

The May 1996 and May 2003 seepage analyses indicate 

that the largest streamflow losses occurred along Reaches 

1 and 2 between Peace River at Wabash (site 2) and Clear 

Springs station (site 11) where the most prominent karst 

features are located. For the two seepage runs, the cumulative losses along Reaches 1 and 2 were similar (-17.3 ft3/s in 

May 1996 and -17.8 ft3/s in May 2003). Streamflow losses 

in Reach 1 during May 1996 and May 2003 were -5.2 and 

-7.1 ft3/s, respectively, and were -12.1 and -10.7 ft3/s in 

Reach 2, respectively (fig. 34A, B). A comparison of these two 

temporally spaced, low-flow seepage runs suggests that the 

relation between the river and groundwater during low-flow 

conditions did not change significantly over the 7-year period 

along Reaches 1 and 2. 

Reach 3 had the largest measured seepage gains of 

all the reaches. Seepage gains in Reach 3 were 4.21, 1.40, 

and 6.08 ft3/s, for May 1996, May 2003, and January 2006, 

respectively (fig. 34A-C). Tributary flow is greatest along this 

reach, and some of these gains may be the result of ungaged 

inflows or other lateral flows that drain slowly to the river 

during low-flow conditions. Reach 3 ponds along most of the 

reach during low-flow conditions, which may reflect the lack 

of karst features along this reach. 

Reach 4 had streamflow losses of -3.13, -0.11 (loss 

within measurement error and not considered significant), and 

-2.46 ft3/s during the May 1996, May 2003, and January 2006 

seepage runs, respectively (fig. 34A-C). There are a number of 

mine outfalls and two tributaries (Rocky and Sink Branch) that 

contribute flow to this section of the river. The losses during 

May 1996 (-3.33 ft3/s) and January 2006 (-2.46 ft3/s) seepage 

runs may indicate the occurrence of karst features in this 

reach, but no discernable features were located. 

Results from the January 2006 (fig. 34C) seepage run 

indicated that in Reach 1, the river gained about 0.7 ft3/s, 

but this gain was within the margin of error of the measurement and was not considered significant. This reach typically 

exhibits water losses during lower stream levels. Reach 1 

has no natural tributaries, but receives flow from two poorly 

incised channels that can receive water from and lose water 

to a series of phosphate-mining pit lakes (fig. 22). These pits 

are located on the eastern side of the Peace River floodplain 

and immediately downstream from the Bartow gaging station, 

and inflows were not monitored during this study. Flows to or 

from these pit lakes can occur when streamflow at the Peace 

River at Bartow station is about 50 ft3/s or more. Discharge 

measured on January 24, 2006, at the Peace River at Wabash 

(site 2) and near Bartow (site 7) was 51.9 and 52.6 ft3/s, 

respectively (table 2). The seepage loss in Reach 2 (between 

site 7 and site 11) was -11.6 ft3/s (fig. 34C). Losses in Reach 2 

were similar to the losses documented in May 1996 and May 

2003 (-12.1 and -10.7, respectively).
50 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida SEEPAGE LOSSES (-) AND GAINS (+), IN CUBIC FEET PER SECOND PEACE RIVER Site 11 ( ) 0.66

Reach 3 Tributary inflow 7.43 ft /s3

Reach 4 Total Tributary Inflow 3.33 ft /s3

Reach 1 Reach 2 Reach 3 Reach 4

Loss -5.2 ft /s3

Gain + 4.21 ft /s3

Site 16 ( ) 12.3

(A) Low baseflow seepage run, May 28-29, 1996

Loss -12.1 ft /s3

Loss -3.13 ft /s3

20

15

10

5

0

-5

-10

-15

-20

Site 8 ( ) 10.1

Site 7 ( ) 12.8

Site 5 ( ) 17.1

Site 3 ( ) 17.4

Site 2 ( ) 18.6

Site 1 ( ) 18.0

Site 31 ( ) 12.5

Reach 3 Tributary nflowi 7.11 ft /s3

Reach 4 Total tributary inflow 3.81 ft /s3

Loss -7.1 ft /s3

Gain + 1.40 ft /s3

Loss -10.7 ft /s3

Loss -0.11 ft /s3

Site 11

( ) 8.69

Site 16 ( ) 17.2

Site 8 ( ) 20.0

Site 7 ( ) 19.4

Site 5 ( ) 24.8

Site 3 ( ) 24.5

Site 2 ( ) 24.4

Site 1 ( ) 26.5

Site 31 ( ) 17.7

(B) Low baseflow flow seepage run, May 13-14, 2003

May 13, 2003 May 14, 2003 Site 16 ( ) 14.0

Site 11

( ) 41.0

Site 7 ( ) 52.6

Site 2 ( ) 51.9

Site 1Site 31

( ) 69.8

Loss -11.6 ft /s3 Reach 3 Tributary nflow 11i .52 ft /s3

Reach 4 Total tributary inflow 13.66 ft /s3

Gain + 6.08 ft /s3

Loss -2.46 ft /s3

Site 16

( ) 58.6

Gain

+0.7 ft /s3

(C) Medium-to-low baseflow seepage run, January 24, 2006

Reach 3 Tributary nflow 10i .73 ft /s3 Reach 4 --tributary flow not measured

Site 11

( )

Site 7 ( )

0.0

11.3

Site 2 ( ) 18.5

Site 1

Site 31 ( ) 13.0*

Site 16 ( ) 9.3*

Site 3 ( ) 17.2

Site 5 ( ) 17.0

Site 10 ( ) 9.0

Loss

-7.2 ft /s3

Loss -1.43 ft /s3

Loss -11.3 ft /s3

0 1 2 3 4 5 6 7 8 9 10 11 12 13

(D) Low baseflow seepage run, June 23, 2006

EXPLANATION

Site 2 ( ) 18.5

Reach 1 Reach 2 Reach 3 Reach 4

20

15

10

5

0

-5

-10

-15

-20

Reach 1 Reach 2 Reach 3 Reach 4

20

15

10

5

0

-5

-10

-15

-20

Reach 1 Reach 2 Reach 3 Reach 4

20

15

10

5

0

-5

-10

-15

-20

DISTANCE, IN MILES DOWNSTREAM FROM THE PEACE RIVER AT BARTOW GAGE (SITE 1) TO PEACE RIVER AT FORT MEADE (SITE 31) GAGE

not significant– within measurement error

Not significant (within measurement error)

May 28, 1996 May 29, 1996

STREAMFLOW SITE NUMBER AND SEEPAGE DISCHARGE

MEASUREMENT ( )—Measurement sites are shown in figure 22. IN RED

*Data obtained from rating curve

Site 9 ( ) 18.3

Figure 34. Comparison of flow losses and gains for seepage runs conducted during (A) May 1996, (B) May 2003, (C) January 

2006, and (D) June 2006 from the Peace River at Bartow to the Peace River at Fort Meade gaging stations.
Streamflow 51

Total seepage loss between Reach 1 and 2

11.6 ft /s (7.5 Mgal/d) 3 Gain +16.6 ft /s3

Loss -11.6 ft /s3

20

10

0

-10

-20

-30

Site 2 ( ) 77.9

Reach 1 Reach 2

Reach 1 Reach 2

Reach 1 Reach 2

Reach 1 Reach 2

Reach 1 Reach 2

Reach 1 Reach 2 Site 7 ( ) 94.5

Site 11 ( ) 82.9

(B) April 23, 2003

Total seepage loss between Reach 1 and 2

13.9 ft /s (9.0 Mgal/d) 3

Gain +8.1 ft /s3

Loss -13.9 ft /s3

20

10

0

-10

-20

-30

Site 2 ( ) 64.6

Site 7 ( ) 72.7

Site 11

( ) 58.5

(C) April 25, 2003

Total seepage loss between Reach 1 and 2

26.1 ft /s (16.9 Mgal/d) Gain +16.7 ft /s 3 3

Loss -26.1 ft /s3

20

10

0

-10

-20

-30

Site 2

( ) 55.6

Site 7

( ) 72.3

Site 11

( ) 46.2

(D) November 6, 2003

Total seepage loss between Reach 1 and 2

29.8 ft /s (19.3 Mgal/d) 3

Loss -10.4 ft /s3

Loss -19.4 ft /s3

20

10

0

-10

-20

-30

Site 2

( ) 47.8

Site 7

( ) 37.4

Site 11

( ) 18.0

(E) June 29, 2004

Total seepage loss between Reach 1 and 2

12.9 ft /s (8.3 Mgal/d) 3

Loss -11.1 ft /s3

20

10

0

-10

-20

-30

Site 2 ( ) 63.0

Site 7 ( ) 61.2

Site 11

( ) 50.1

(F) March 2, 2006 20

10

0

-10

-20

-30

Total seepage loss between Reach 1 and 2

14.4 ft /s (9.3 Mgal/d) 3

Loss -9.4 ft /s3

20

10

0

-10

-20

-30

Site 2

( ) 13.8

Site 7

( ) 8.73

Site 11

( ) -0.64

(G) March 30, 2006

Loss -1.8 ft /s3

Loss -5.1 ft /s3

0.8 1.5 2.0 2.5 3.0 3.5 3.7

DISTANCE, IN MILES DOWNSTREAM FROM THE PEACE RIVER AT BARTOW GAGE (SITE 1)

TO PEACE RIVER AT CLEAR SPRINGS GAGE (SITE 11)

PEACE RIVER SEEPAGE LOSSES (-) AND GAINS (+), IN CUBIC FEET PER SECOND

1.0

EXPLANATION

Site 2 ( ) 13.8 STREAMFLOW SITE NUMBER AND SEEPAGE DISCHARGE

MEASUREMENT ( )—Measurement sites are shown in figure 22. IN RED

Reach 2

Site 2

(41.0*)

Site 7

( ) 18.3

Site 11

( ) 8.88**

(A) June 28, 2002

Reach 1

*Estimated discharge from rating curve

**Reverse flow of 8.88 ft /s

from Sixmile Creek

3

Loss -22.7 ft /s3Loss -27.7 ft /s3

Total seepage loss between Reach 1 and 2

49.9 ft /s (32.2 Mgal/d) 3

Figure 35. Streamflow losses along Reaches 1 and 2 from the Peace River at Wabash (site 2) to the Peace River 

at Clear Springs gaging stations (site 11).
52 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Table 2. Computed and measured discharge at selected sites and total streamflow losses along Reaches 1 and 2 during below-average 

flow conditions.

[Sites shown in fig. 22. Discharge in cubic feet per second (ft3/s). USGS discharge measurement error estimated at ±5 to 8 percent. Numbers shaded in blue 

represent instantaneous discharge obtained from the rating curve at Peace River at Bartow. Numbers shaded in yellow indicate flow reversal originating from 

Sixmile Creek. –, site not measured; e, estimated; 0, zero flow was observed. Below average flow conditions reflect periods when streamflow was less than 

100 ft3/s at Peace River at Bartow. During below average conditions, streamflow measurements for the Peace River at Bartow (site 1) were made at Peace River 

at Wabash (site 2)]

Date

Instantaneous and measured discharge (cubic feet per second)

Total loss 

Site 1 Site 2 Site 3 Site 4 Site 5 Site 6 Site 7 Site 8 Site 9 Site 9a Site 10 Site 11

Reach 1 Reach 2

 2002 Water Year 

5/17/2002 0 0 0 0 0 0 0 0 0 0 0 0 0

5/20/2002 – 7.34 2.52 0.22 0.2 0 0 0 0 0 0 0 -7.34

6/11/2002 – 12.6 7.7 – 1.8 1.18 0 0 0 0 0 0 -12.6

6/14/2002 – 4.5 1.24 0.79 0.19 0 0 0 0 0 0 0 -4.5

6/19/2002 7.7 – – – – – – – – – – 2.50 1

-10.2

6/20/2002 9.8 – – – – 5.54 0 0 0 0 0 5.06 2

-14.9

6/24/2002 24 – – – 12.2 4.71 0 0.85 0 0 0 2.91 3

-26.9

6/25/2002 – 28.1 22.6 – – – 7.95 5.37 2.0 0 0 0 -28.1

6/26/2002 37 – – – – – 15.1 – – 3.02 0 0 -37.0

6/28/2002 41 – – – – – 18.3 – – – 3.82 8.88 4

-49.9

 2003 Water Year

4/23/2003 – 77.9 – – – – 94.5 – – – – 82.9 5-11.6

4/25/2003 – 64.6 – – – – 72.7 – – – – 58.5 6-14.2

5/13/2003 26.5 24.4 24.5 – 24.8 – 19.4 20.0 18.3 – – 8.69 -17.8

 2004 Water Year

11/06/2003 57.4 55.6 – – – – – – – – – 46.2 -11.2

3/09/2004 81 – – – – – 86.3 – – – – 68.2 7

-18.1

4/27/2004 – 14.3 – – – – 8.44 – – – – 0 -14.3

5/19/2004 – 10.9 – – – – 3.98 – – – – 0 -10.9

6/01/2004 – 4.36 – – – – 0 0 0 0 0 0 -4.36

6/29/2004 – 47.8 – – – – 37.4 – – – – 18.0 -29.8

 2006 Water Year

1/24/2006 – 51.9 – – – – 53.7 – – – – 41.0 8-12.7

3/02/2006 – 63.0 – – – – 61.2 – – – – 50.1 -12.9

3/13/2006 – 28.0 – – – – 22.7 – – – – 15.8 -12.2

3/30/2006 – 13.8 – – – – 8.73 – – – – 0.64 9-14.4

4/11/2006 – 11.0 – – – – 4.62 – – – 1.44 0 -11.0

5/18/2006 17 – – – – – – – – – 2.34 0 -17.0

5/30/2006 – 6.12 – – – – – – – – – 0 -6.12

6/8/2006 4.4 – – 3.0e – 0.50e 0 0 0 0 0 0 -4.40

6/12/2006 27 – – – – – – – – – 16.1 0 -27.0

6/23/2006 – 18.5 17.2 – 17.0 – 11.3 – – – 9.00 0.83 10-19.3

 2007 Water Year

10/11/2006 34 – – – – – 31.5 – – – – 22.5 -11.5

11/14/2006 – 9.64 – – – – 4.13 – – – 0.71 0 -9.64

2/08/2007 49 – – – – – 46.4 – – – – 37.1 -11.9

3/23/2007 – 14.2 – – – – 6.67 – – – 3.04 0 -14.2

5/11/2007 – 1.45 – – – – 0 – – – 0 0 -1.45

5/15/2007 – 0.10e 0 0 0 0 0 0 0 0 0 0 -0.10e

6/13/2007 13 – – – – – 2.36 – – – 0 0 -13.0

7/18/2007 – 4.29 – – – 1.5e 0 0 0 0 0 0 -4.29

8/29/2007 17 – – – – – 7.91 – – – 2.5e 0 -17.0

1Flow loss of 7.7 ft3

/s and reverse flow of 2.50 ft3/s from Sixmile Creek to Dover Sink for a total flow loss of -10.2 ft3/s for Reaches 1 and 2. 2

Flow loss of 9.8 ft3/s and reverse flow of 5.06 ft3/s from Sixmile Creek to Dover Sink for a total flow loss of -14.9 ft3/s for Reaches 1 and 2. 3Flow loss of 24 ft3/s and reverse flow of 2.91 ft3

/s from Sixmile Creek to Dover Sink for a total flow loss of -26.9 ft3/s for Reaches 1 and 2. 4

Flow loss of 41 ft3/s and reverse flow of 8.88 ft3/s from Sixmile Creek to Dover Sink for a total flow loss of -49.9 ft3/s for Reaches 1 and 2. 5Gain of 16.6 ft3/s in Reach 1 and a flow loss of -11.6 in Reach 2. 6

Gain of 8.1 ft3/s in Reach 1 and a flow loss of -14.2 in Reach 2. 7Gain of 5.3 ft3/s in Reach 1 and a flow loss of -18.1 in Reach 2. 8Gain of 1.8 ft3/s in Reach 1 and a flow loss of -12.7 in Reach 2. 9Flow loss of 13.8 ft3/s and reverse flow of 0.64 ft3/s from Sixmile Creek to Dover Sink for a total loss of -14.4 ft3

/s for Reaches 1 and 2. 10Flow loss of 18.5 ft3/s and reverse flow of 0.83 ft3/s from Sixmile Creek to Dover Sink for a total loss of -19.3 ft3/s for Reaches 1 and 2.
Streamflow 53

A comparison of seepage runs was conducted on May 

1996 (fig. 34A) and June 2006 (fig. 34D) when the discharge 

in the river at the beginning of Reach 1 was 18.6 and 18.5, 

respectively. These seepage runs indicated that during belowaverage streamflow and groundwater conditions, and when the 

discharge at Peace River at Bartow was less than about 20 ft3/s 

(±5 to 8 percent error), all of the flow in the river drained into 

various karst features and flow usually ended within Reach 2. 

During the 2007 water year, the annual mean discharge was 

only 18 ft3/s and for most of the water year, the flow ended at 

various karst features in Reaches 1 and 2.

A number of smaller seepage runs (about 3 mi) were 

conducted once the area of greatest streamflow losses was 

identified. Both streamflow losses and gains were noted in 

Reach 1 during below-average conditions, whereas losses 

consistently occurred in Reach 2 (fig. 35; table 2). Flow losses 

for the combined reaches ranged from 0.1 to about 50 ft3/s 

and were dependent on the amount of discharge in the river 

and water levels in the aquifers. The greatest flow loss for 

Reaches 1 and 2 of about 50 ft3/s (32 Mgal/d) was measured 

on June 28, 2002 (fig. 35A; table 2). This large loss occurred 

at the beginning of the summer rainy season when discharge 

in the river increased and large volumes of water were needed 

to replenish unfilled cavities and void spaces in the underlying 

aquifers. 

Karst Features along the Upper Peace River 

Based on the series of seepage runs, an approximate 2-mi 

section of the upper Peace River was determined to be a highly 

karstified region where numerous features were located that 

were capable of draining the river water (fig. 36). Surveys 

were conducted when the riverbed was dry to locate the karst 

features. These surveys indicated that a number of prominent 

karst features were located in both the low- and high-water 

channels (Knochenmus, 2004). Most of the high-water 

(floodplain) karst features showed evidence of surface-water 

inflows. Locations of these karst features were documented and 

dimensions and surface orientations were measured. Not all of 

the karst features along the upper Peace River were located, 

because they were inaccessible or covered by vegetation; therefore, additional buried features probably exist. Locations of the 

most prominent karst features for Reaches 1 and 2 are shown in 

figure 36, and the names, dimensions, and a brief description of 

the karst features for Reaches 1 through 4 are listed in table 3. 

The karst features that were located in Reaches 1 and 2 

consist of a variety of erosional features, such as cracks in 

the river channel limestone bedrock (Crevasses and Ledges 

Sinks): a large conduit system at the base of a highly fractured 

outcrop or swallet (Dover Sink); holes in the bedrock due to 

cypress root growth (near Wabash Complex); a series of interconnected karst windows (Catacombs Nos. 1-9); vertical pipes 

(Fricano Fracture, Wabash Sink, and Cook’s Ripple); and 

buried sinks or collapsed channel bedrock that subsequently 

infilled with sediments (Catfish, Midway, and Elephant 

Graveyard Sinks). Some of the prominent karst features found 

in the upper Peace River karst area are shown in figure 37. 

After the initial survey, several more prominent features were 

located, including Catfish Sink (Reach 2), Liz Sink (Reach 2) 

and Tom’s Sink (Reach 3). Otter Sink, adjacent to Kissengen 

Spring (Reach 3), developed and expanded during the course 

of this investigation. The prominent karst features located 

along Reach 3 are shown in figure 22.

During this investigation, most karst features were altered 

to some degree due to depositional processes, such as scouring 

and sediment infilling. During 2002, many karst features were 

exposed and could be easily identified. However, subsequent field surveys after the 2004 hurricane season and the 

high-water period of 2005 indicated that some karst features 

had silted in and had become unidentifiable. Midway Sink, 

Elephant Graveyard, Fricano Fracture, Harley, and Jackson 

Sinks were no longer exposed, and Ledges, Cook’s Ripple, 

and Crevasses Sink became partially silted in. Rainfall and 

streamflow were below average during the 2006-2007 water 

years, and the stream channel was dry during much of this 

time. This condition led to increased scouring by wind and the 

energy from infrequent streamflow events, which removed 

sediment and re-exposed some of the features. Dover Sink 

has undergone the most significant changes, which will be 

discussed in more detail in a later section.

Streamflow Losses to Karst Features 

The following section describes the characteristics of 

karst features in Reaches 1 and 2 and the measured streamflow 

losses to the karst features. Streamflow losses to the karst 

features in Reaches 1 and 2 are listed in table 4. These karst 

features are characterized in an upstream to downstream order, 

and streamflow losses are expressed as negative values (-), to 

contrast with gains to the river from tributary inflows, which 

are expressed as positive values (+). Measurable streamflow 

losses were not observed in the low-water channel along 

Reach 3, although a limited description of the high-water 

channel karst features that are present along this reach is 

included in table 4. Karst features were not identified in 

Reach 4.

Some of the most influential karst features located in 

and along the Reach 1 channel bed include the Wabash Sink, 

Cypress Root Sink, Cook’s Ripple, Fricano Fracture, Ledges 

Sink, and the adjoining Catacombs Complex, which is located 

in the floodplain (fig. 38A-F). During different time periods of 

this investigation, flow in the river was observed terminating 

at the following sinks: Wabash Sink, Cypress Root Sink, 

Cook’s Ripple, Fricano Fracture, and Ledges Sink. In Reach 1, 

the largest loss of water from the river to the groundwater 

system persistently occurred at Ledges Sink, a fracture in the 

riverbed. 

The Wabash Complex consists of several small karst 

features (Wabash Sink, Corbett Sink, and Cypress Root Sink), 

and it is the first notable karst complex in the long series 
54 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

of features that line the low-water channel along Reach 1 

(fig. 36, site 2; fig. 38A-B). The complex spans a section of 

about 450 ft along the Peace River channel, which is located 

about 690 ft east of the Bartow Waste Water Treatment 

Plant. Wabash Sink, the most active sink in the complex, is 

a vertical pipe karst feature located at the eastern edge of the 

low-water channel. During low-flow conditions, river water 

that flows into this vertical pipe creates a circular whirlpool, 

which formed this conduit into its round vertical shape. 

A number of flow measurements were made at this feature 

during 2002-2006, and losses ranged from -0.30 to -5.50 ft3/s 

(table 4). 

Cook’s Ripple is a karst feature located in the western 

edge of the channel bed, about 0.5 mi downstream from 

Wabash Sink (fig. 36, site 4; fig. 38C). The feature is a 

vertical pipe that drains a relatively small amount of flow 

from the Peace River at low river stages. Flow in the lowwater channel is diverted to Cook’s Ripple by a narrow 

distributary channel; however, under higher flow conditions, the distributary channel and feature are inundated. 

Flow that enters this vertical pipe also creates a circular 

whirlpool, indicating downward flow. Although this site 

has been infilled with sand since the initial survey of 2002, 

the amount of diffuse inflow into this sink does not appear 

to have diminished based on subsequent field observations. 

In 2002, measured flow losses to this feature were -0.45 and 

-2.30 ft3/s (table 4).

Fricano Fracture is a small vertical pipe located at the 

eastern edge of the low-water channel and 0.2 mi downstream from Cook’s Ripple (fig. 36, site 5; fig. 38D). Water 

that flows down the pipe also creates a small circular whirlpool, further indicating downward flow. This sink became 

filled with silt following the 2004 hurricanes and subsequent 

high-water period. Two measurements were made at this 

sink in 2002 when the flow in the channel ended at this site; 

measured losses were -0.22 and -0.19 ft3/s (table 4).

Ledges Sink is the most prominent karst feature along 

Reach 1 and, depending on hydrologic conditions, this sink 

can drain a large volume of water from the stream channel 

(fig. 36, site 6; fig. 38E). Ledges Sink is a fracture in the 

limestone bedrock that is exposed in the riverbed. This 

feature is located near the edge of the channel about 1.6 mi 

downstream from the SR 60 bridge at Bartow. The fracture 

is about 26 ft long and is oriented in a north-south direction. 

The fracture displaces the limestone bedrock slightly and 

elevates it above the channel bed. This displacement allows 

river water to flow directly under this limestone bedrock 

ledge. Discharge measurements to this feature were made 

under various flow conditions from 2002 to 2006, and losses 

ranged from -1.18 to -7.49 ft3/s (table 4). Field observations 

indicated that when the flow at the Peace River at Bartow 

gaging station (site 1) was about 10 ft3/s, the upper Peace 

River flow typically terminated at this sink.

KARST FEATURE Name

and site number

KARST FEATURE

ORIENTATION

GAGING STATION Name

and site number

—

—

81°49’ 81°48'

27°54’

27°53'

27°52’

0

Peace River at Bartow (1)

Crevasses Sink (9B)

Paternoster Complex (9C)

Dover

Sink (10)

Gator Sink (10B)

Log Sink

(10A)

Peace

Sixmile Creek (12)

Catfish Sink (9A)

Liz Sink

(10C)

River

Wabash Sink

(used as alternate for

discharge

measurement during

low-water)

site for

(2)

1

Cypress Root

Corbett Sink (3)

Fricano Fracture (5)

Ledges Sink (6)

Peace River

near Bartow (7)

Catacombs

Complex

Elephant Graveyard (9)

Midway

Sink (8)

Harley Sink

Cook's

Ripple (4)

Peace River at Clear

Springs (11)

REACH 1

REACH 2

Area of river channel

that ponds and does

not go dry

Wabash Complex

Jackson Sink

EXPLANATION

Sixmile Creek

0

0.5 MILE

0.5 KILOMETER

Cook's

Ripple (4)

Sixmile

Creek (12)

Figure 36. Location of karst features in Reaches 1 and 2. 
Streamflow 55

During receding flow periods a large number of fish die off, 

as shown here at Dover Sink, August 2, 2007.

Photo credit: Charles Cook, FDEP

Table 3. Location and description of major karst features along the upper Peace River.

[Features are listed from north to south, ddmmss.s, degrees, minutes, and seconds; No., number; ft, feet; E, east; W, west; N, north; S, south]

Karst feature1 Latitude

ddmmss.s

Longitude

ddmmss.s 

Length

(feet)

Width

(feet) Description

Wabash Sink 275336.2 814838.6 26 17 Vertical pipe; formed near cypress tree roots

Cypress Root Sinks 275334.0 814836.0 5 5 Two sinks in channel; formed by cypress roots

Corbett Sink 275334.0 814837.0 39 39 Sink located off the low-water channel about 50 ft

Cooks Ripple 275315.0 814828.9 15 10 Vertical pipe; small channel diverts flow to feature

Fricano Fracture 275307.0 814823.0 3 2 Vertical pipe located on eastern side of channel

Harley Sink 275302.0 814821.0 4 4 Vertical pipe: infilled with sediments after 2004 hurricanes

Ledges Sink 275300.2 814822.8 26 10 Crack in river channel bedrock; next to Catacombs

Catacombs No. 1 275303.8 814824.4 38 30 Karst window; 8 ft deep; most noticeable flow

Catacombs No. 2 275303.0 814825.7 35 20 Karst window; 4 ft deep; noticeable flow 

Catacombs No .3 275303.7 814824.4 36 24 Karst window; 7 ft deep; reduced flow

Catacombs No. 4 275303.2 814825.3 28 17 Karst window; 4.5 ft deep

Catacombs No. 5 275302.8 814826.8 16 14 Karst window; root formed sink; 6 ft deep 

Catacombs No. 6 275302.6 814825.8 17 18 Karst window; root formed sink; 5 ft deep

Catacombs No. 7 275302.1 814826.7 15 15 Karst window; root formed sink; 4.5 ft deep

Catacombs No. 8 275302.0 814827.2 22 15 Karst window; sounds of water in sink; about 12 ft deep

Catacombs No. 9 275302.8 814826.8 14 16 Karst window; two sinks close together; about 15 ft deep

Jackson Sink 275300.0 814822.0 5 3 Vertical pipe; infilled with sediments after 2004 hurricanes

Midway Sink 275254.0 814806.0 22 9 Collapsed channel bedrock, infilled with sediments in 2005 

Elephant Graveyard Sink 275248.0 814807.0 8 8 Collapsed channel bedrock, infilled with sediments in 2005

Catfish Sink 275236.6 814806.6 50 25 Buried sink; traps aquatic life during low-flow periods

Crevasses Sink (E-W) 275229.0 814809.0 26 2 Crack in river channel bedrock; about 5 ft deep

Crevasses Sink (N-S) 275229.0 814809.1 9 2 Crack in river channel bedrock; about 7 ft deep

Paternoster Complex 275228.0 814805.0 70 62 Three sinks in high-water floodplain

Gator Sink 275226.0 814819.0 90 72 Large round sinkhole; river water is diverted to sink during higher flows

Log Sink 275223.0 814814.0 66 44 Drains river water during medium to high flows

Dover Sink 275222.0 814806.0 91 55 Swallet; drains largest volume of flow of all sinks

Liz’s Sink 275220.8 814808.7 23 60 Collapsed limestone in high-water channel; evidence of inflow

Kissengen Spring 275033.3 814839.3 95 126 Dry; ponds during wet periods due to backwater from river

Otter Sink 275032.7 814841.5 30 20 Next to Kissengen Spring; developed during study

Tom’s Sink 275032.8 814830.1 50 50 Collapsed limestone in high-water channel; evidence of inflow 

1Locations of features are shown in figs. 13B and 36.
56 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

(A) Crevasse or crack (Crevasses Sink) (B) Swallet or sink (Dover Sink)

(C) Root-filled cavity (near Wabash Complex) (D) Karst window (Catacombs No.3)

(E) Vertical pipe (Fricano Fracture) (F) Buried sink (Catfish Sink)

Photo credit: Charles Cook, FDEP Photo credit: Charles Cook, FDEP

Photo credit: Lari Knochenmus, USGS Photo credit: Charles Cook, FDEP

Photo credit: P.A.Metz, USGS Photo credit: P.A.Metz, USGS

Figure 37. Examples of karst features along the upper Peace River.
Streamflow 57

Table 4. Discharge measurements of streamflow losses to karst 

features in Reaches 1 and 2 along the upper Peace River.

[Discharge in cubic feet per second; –, no measurement; bold numbers indicate

the difference in discharge measured upstream and downstream of a karst feature; 

shaded numbers indicate that upstream flow ended at a karst feature]

Site 

number

(fig. 36)

Karst 

feature 

name

Station 

number1

Measurement 

date

Upstream 

discharge

Downstream 

discharge

Streamflow 

loss or 

gain to 

karst 

feature

2 Wabash 

Complex

02294648 5/20/2002 7.34 2.52 -4.82

6/11/2002 12.6 7.70 -4.90

6/14/2002 4.5 1.24 -3.26

6/25/2002 28.1 22.6 -5.50

4/25/2003 64.6 65.2 2+0.60

5/13/2003 24.4 24.5 2+0.10

6/04/2003 52.2 51.9 -0.30

6/23/2006 18.5 17.2 -1.30

4 Cook’s 

Ripple

02294665 5/20/2002 2.52 0.22 -2.30

6/14/2002 1.24 0.79 -0.45

5 Fricano 

Fracture

02294670 5/20/2002 – – -0.22

6/14/2002 -0.19

6 Ledges 

Sink

02294672 6/11/2002 – – -1.18

6/20/2002 – – -5.54

6/24/2002 12.2 4.71 -7.49

5/13/2003 24.8 19.4 -5.40

6/23/2006 17.0 11.3 -5.70

8 Midway 

Sink

02294692 6/24/2002 – – -0.85

6/25/2002 5.37 2.0 -3.37

9 Elephant 

Graveyard 

Sink

02294695 6/25/2002 – – -2.0

5/13/2003 20.0 18.3 -1.70

9B Crevasses 

Sink

02294700 6/26/2002 – – -3.02

10B Gator Sink 2752260814819 7/03/2002 – – 3-1.38

8/13/2002 – – 3-3.20

10 Dover 

Sink

02294705 6/19/2002 – – 4-2.50

6/20/2002 – – 4-5.06

6/24/2002 – – 4-2.91

6/28/2002 – – 5-12.7

5/18/2006 – – 6

-2.34

6/12/2006 – – 7-16.1

6/23/2006 – – 8-9.83

1

Station number corresponds to downstream order number or latitude and 

longitude in degrees, minutes, and seconds. 2Streamflow gain most likely the result of inherent discharge measurement 

error of 5 to 8 percent. 3Discharge measured at Gator Sink Distributary.

4Total discharge source is from Sixmile Creek.

5Discharge source is 8.88 ft3

/s from Sixmile Creek and 3.82 ft3/s from the 

Peace River. 6Total discharge source is from the Peace River.

7Total discharge source is from the Peace River during Tropical Storm Alberto.

8

Discharge source is 0.83 ft3/s from Sixmile Creek and 9.00 ft3/s from the 

Peace River.

Underlying Ledges Sink is a large cavity that receives 

the inflow from the river. Barr (1992) documented this 

feature as an open swallow hole in the riverbed with an 

underlying cavern large enough to accommodate several 

standing individuals. This open swallow hole is no longer 

visible in the riverbed because of infilling of channel 

sediments. Currently (2008), the water flows downward 

into the cavern and moves in a westerly direction through 

a series of contiguous karst features that are termed the 

Catacombs Complex. These features are located in the 

high-water channel and are composed of about 9 interconnected karst windows in which flow can be observed 

moving from one sink to another. 

The flow entering Ledges Sink reappears in the 

floodplain about 75 ft west of the river edge within the 

Catacombs Complex (fig. 36; fig. 38F). Flow is often 

visible in a large cavernous area called Catacombs No. 1, 

which is about 30 by 38 ft. The visible flow in the deepest 

part of the karst window is about 8 ft below land surface, 

and can be observed moving swiftly at a velocity of about 

1 ft/s. The flow from Catacombs No. 1 moves in a westerly direction to a series of smaller karst windows where 

velocities decline substantially. The length of the complex 

from Catacombs No. 1 to the termination of the sinks is 

about 450 ft. The smaller sinkholes appear to have been 

created by a loss of support of the underlying limestone, as 

well as by tree roots that have broken through the limestone bedrock. All streamflow losses to the Catacombs 

Complex are considered to be the same as the losses at 

Ledges Sink, because these features are interconnected.

The most influential karst features located in 

Reach 2 include the following: Midway, Elephant 

Graveyard, Catfish, Crevasses, Dover, and Gator Sinks 

(fig. 36). Some of the prominent karst features in 

Reach 2 are shown in figure 39. During this investigation, Reach 2 experienced the greatest number of days 

when the riverbed went dry, and the largest volume of 

streamflow losses recorded along the upper Peace River. 

During different time periods in this investigation, flow in 

Reach 2 was observed terminating at the following sinks: 

Elephant Graveyard, Crevasses Sink, and Dover Sink. 

Midway Sink and Elephant Graveyard are first in 

the series of sinks located along Reach 2 (fig. 36, sites 8 

and 9). Midway Sink and Elephant Graveyard are located 

about 230 and 1,500 ft south of the Peace River near 

Bartow gaging station, respectively. Midway Sink is a 

collapsed feature located near the edge of the low-water 

channel that contains small fractures at its base (fig. 39A). 

Elephant Graveyard is downstream from Midway Sink, and 

consists of a series of limestone outcrops and depressions 

in the low-water channel bed. The area between these two 

sinks also had observable diffuse seepage losses, but these 

were not measured directly. Therefore, the diffuse losses 

were included in the flow losses for Elephant Graveyard. 

Measurements made at Midway Sink were -0.85 and 

-3.37 ft3/s, and measurements made at Elephant Graveyard 
58 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

(A) Wabash Sink (part of Wabash Complex)

(C) Cook’s Ripple (D) Fricano Fracture

(B) Cypress Root Sink (part of Wabash Complex)

(E) Ledges Sink (F) Catacombs No. 1

Photo credit: Lari Knochenmus, USGS

Photo credit: Charles Cook, FDEP

Photo credit: Lari Knochenmus, USGS

Photo credit: P. A. Metz, USGS

Photo credit: P. A. Metz, USGS Photo credit: P. A. Metz, USGS

Figure 38. Karst features in Reach 1 along the upper Peace River.
Streamflow 59

(A) Midway Sink (C) Crevasses Sink

(B) Catfish Sink

(D) Gator Sink (E) Gator Sink Distributary

Photo credit: Lari Knochenmus, USGS

Photo credit: Charles Cook, FDEP

Photo credit: P. A. Metz, USGS

Photo credit: P. A. Metz, USGS Photo credit: P. A. Metz, USGS

Figure 39. Karst features in Reach 2 along the upper Peace River.
were -1.70 and -2.0 ft3

/s (table 4). Sediment deposition caused 

by the high flows from the hurricanes of 2004 buried these 

sinks, and they could not be identified until 2008. Because of 

the deposition and high- or no-flow conditions, flow measurements were not conducted at these sites after 2003. 

Located 0.4 mi south of Elephant Graveyard is a diffuse 

seepage feature named Catfish Sink (fig. 36, site 9a; fig. 39B). 

This feature was discovered late in the investigation (2006), 

and flow measurements were not obtained at this site. The 

large volume of water that flowed down the dry channel bed 

from Tropical Storm Albert (June 12, 2006) filled this sink at 

a rate of about 2 to 3 ft3/s within 30 minutes. However, typical 

diffuse seepage losses are probably less than 1 ft3/s during 

varying hydrologic conditions based on measured streamflow 

losses along this reach. During receding flow periods, a large 

accumulation of dead catfish and debris usually settles over 

this feature.

The Crevasses Sink is a series of solution fractures in the 

limestone river bedrock located about 600 ft downstream from 

Catfish Sink (fig. 36, site 9b; fig. 39C). The longest fracture 

is about 26 ft long and is oriented in an east-west direction, 

spanning most of the low-water channel. An adjacent smaller 

fracture, about 9 ft long and oriented in a north-south direction, is located at the western edge of the channel. This feature 

is similar to Ledges Sink, consisting of a large exposed 

fracture in the channel bed and a large underlying cavity that 

receives flow from the river and drains into the underlying 

aquifers. Crevasses Sink receives water from the stream 

channel on a continual basis, but at a lower rate than the 

Vultures await their meal of snakes and 

fish stranded at Catfish Sink. 

Photo credit: Charles Cook, FDEP

Photo credit: P.A. Metz, USGS
Streamflow 61

Photo credit: P.A. Metz, USGS

similar Ledges Sink. A number of field observations during 

2006-2007 indicated that flow from the upper Peace River 

terminated at this sink. Measured flow loss at Crevasses Sink 

during June 26, 2002 was -3.02 ft3/s (table 4).

Gator Sink is one of the largest of the documented sinkholes and has a “classic” circular shape. The sinkhole is 90 ft 

long, 72 ft wide and 40 ft deep (fig. 36, site 10b; fig. 39D). 

The beginning of the distributary to Gator Sink is located 

about 880 ft downstream from Crevasses Sink on the western 

edge of the floodplain. The sink is located about 800 ft west of 

the river’s edge, where a poorly incised distributary channel 

drains water from the Peace River at a river stage elevation 

of about 88 ft above NGVD 1929. As the river rises, flow in 

this distributary eventually drains into Gator Sink (fig. 39E). 

Gator Sink—A strong current of flow enters the western wall 

of the sinkhole; note the movement of duck weed on the water 

surface from the inflow (above). 

Sinkhole wall, showing the sequence of sand, clay, dolomite, 

and limestone (right). 

Photo credit: P.A. Metz, USGS

Streamflow 61
62 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

When the storage capacity of Gator Sink is reached and the 

water level continues to rise, the sink overflows, inundating 

the surrounding floodplain. Two discharge measurements 

were made in July and August of 2002 at the Gator Sink 

Distributary, with flows draining into the sink at -1.38 and 

-3.20 ft3/s (table 4).

The steep vertical walls of Gator Sink contain, from top 

to bottom, a sequence of sand, clay, dolomite, and limestone 

of the Peace River and the Arcadia Formations (see photos on 

p. 61). The lower sequence of limestone and dolomite forms a 

wall containing cracks, fractures, holes, and vugs. Depending on 

hydrologic conditions, these fractures and cavities occasionally 

transmit water to the sink. During low-flow periods when the 

bottom of the western wall of the sink was exposed, a strong 

current of flow could be observed moving into the sink about 

30 ft below the land surface. A dye test conducted during this 

study indicates that some of the river water that flows into 

Ledges Sink and the Catacomb Complex moves southward 

about 0.75 mi (in less than 1 day) within the shallow karst 

floodplain geology to Gator Sink, then drains into the sink 

through the eroded western wall.

 Other karst features located in the high-water channel of 

Reach 2 include the Paternoster Complex (consisting of three 

sinks), Log Sink, and Liz Sink (fig. 36). Evidence of seepage 

flow has been observed around each of these sinks, but the 

actual losses are unknown. A number of undiscovered sinks 

probably exist within the high-water channel along Reach 2, 

but dense vegetation makes these sinks difficult to locate. 

Dover Sink, located in the eastern floodplain about 0.6 mi 

upstream from the Clear Springs gaging station (fig. 36, 

site 10), had the largest streamflow losses of all the karst 

features along the upper Peace River. Flow from the Peace 

River has eroded an approximate 500-ft-long distributary

channel to Dover Sink (fig. 40A, 41D). The dimensions of 

Dover Sink are about 55 by 91 ft, and the size is continuously 

changing because of depositional and erosional processes. 

The bottom elevation of Dover Sink is presently about 13 ft 

below the elevation of the confluence of the Peace River 

and the distributary channel (fig. 40B). This steep elevation 

change allows large volumes of water to drain into the sink. 

At the bottom of the sink, the flow moves through a horizontal 

erosional crack in the wall of the Arcadia Formation. 

Rhodamine dye, as seen through a karst window (Catacombs No. 1). Photo credit: P.A. Metz, USGS
Streamflow 63

Observations made during this study indicate that an 

extensive interconnected series of cavities exists beneath the 

walls of Dover Sink that can store large volumes of water. 

During the dry season, large unfilled cavities exist in the karst 

system that is connected to Dover Sink. When the rainy season 

returns, river water flows into Dover Sink and replenishes 

these void spaces in the underlying aquifers. 

The interconnected karst system associated with Dover 

Sink is estimated to store more than 10 Mgal in a day before 

the level in the sink stabilizes. This estimate was based on 

(1) a discharge measurement of 16.1 ft3/s made on June 12, 

2006 (table 2; site 10) at Dover Sink Distributary after a 

storm event while aquifer levels were low; (2) a hydrograph 

of water levels of Dover Sink during this time period; and 

(3) streamflow conditions at the downstream Peace River near 

Clear Springs gaging station. Once the local aquifer storage 

volume was replenished, the pool surrounding Dover Sink and 

the distributary rose to the level of the Peace River at about 

87 ft above NGVD 1929, and aquifer levels of the underlying 

interconnected aquifers were about 78 ft above NGVD 1929. 

A number of discharge measurements were made in the Dover 

Sink Distributary, and flow losses into Dover Sink ranged 

from -2.34 to -16.1 ft3/s (table 4).

Dover Sink exhibited the most structural changes of all 

the karst features observed during the period of investigation. 

The series of photographs in figure 41 shows Dover Sink 

over a range of hydrologic conditions. At the beginning of 

the study in 2002, the Dover Sink Distributary channel was 

mostly a sand-filled waterway with small remnant lenses of 

the Bone Valley Formation exposed in the distributary channel 

and exposed rocks of the Arcadia Formation in the main sink 

(fig. 41A). After the hurricanes in 2004 and high-water period 

in 2005, sediment accumulated in Dover Sink and covered 

much of the exposed rock (fig. 41B). Intermittent flows during 

2006-2007 caused greater flow velocities in the distributary 

channel that washed away overlying sediments, exposing 

large limestone boulders of the Arcadia Formation (fig. 41C). 

This erosional exposure created a cascading waterfall effect at 

the approach to Dover Sink (fig. 41D). As a result of several 

high-water events at the end of the 2007 water year, sediment 

again accumulated and covered some of the exposed rocks 

(fig. 41E). The photograph in figure 41F shows Dover Sink 

in a ponded condition after the interconnected karst aquifer 

system was replenished.

At the beginning of this investigation (2002), water 

entered the groundwater system from Dover Sink through a 

horizontal erosional crack at the bottom wall of Dover Sink. 

By the end of the study (2007), however, the force of moving 

water had scoured and enlarged the opening in the wall, which 

then measured about 3 ft in diameter. This enlarged opening 

allowed large quantities of water, sediment, aquatic life, and 

debris to flow into the conduits and cavities associated with 

the underlying aquifers.

 In addition to the erosion of sediment and carbonate 

bedrock in the distributary channel, about 2 ft of erosion 

occurred along the Peace River channel bed at its confluence 

with Dover Sink Distributary. Over time, the erosion in the 

channel has aided in the diversion of flow from the Peace 

River to Dover Sink. Elevation profiles of the Peace River 

channel and Dover Sink Distributary are shown in figure 42. 

In addition to the erosion of the channel, sand also was 

deposited downstream from the confluence of the distributary, 

which aided in the diversion of flow to the sink. Based on 

elevation profiles, the extent of this erosional activity begins 

upstream near Crevasses Sink and ends about 200 ft downstream from the confluence of Peace River and Dover Sink 

Distributary (fig. 42).

About 0.7 mi downstream from Dover Sink is Sixmile 

Creek, which is a phosphate-mine outfall tributary to the Peace 

River (fig. 36, site 12). The area around the confluence of 

Sixmile Creek and Peace River has never been observed to go 

dry, but it does pond during low-flow conditions. As Sixmile 

Creek discharges into this ponded area of the river, the river 

rises enough for a gradient to form, causing an unusual case 

of flow reversal along the river. The water from this ponded 

area travels north about 1,500 ft and eventually discharges 

into Dover Sink. However, a fraction of the discharge in the 

ponded area still flows in the southward downstream direction. 

Figure 43A is a photograph showing the input from Sixmile 

Creek flowing north and the Peace River flowing south, with 

both flows merging into Dover Sink Distributary. A number 

of discharge measurements were made to document this 

reversal of flow, which ranged from 0.83 to 8.88 ft3/s (table 2). 

A discharge hydrograph shows the periods when the discharge 

at Sixmile Creek is greater than discharge from Peace River 

at Clear Springs (flatline indicates no flow; fig. 43B). During 

these peak discharge events for Sixmile Creek, flow was 

observed moving north toward Dover Sink. 

Although there were no notable karst features in the lowwater channel of Reach 3, there were several karst features of 

interest in the high-water channel. These features are Otter and 

Tom’s Sinks, which are located near the historic Kissengen 

Spring (fig. 22). Otter Sink formed in 2002 and drains river 

water during periodic seasonal floodplain inundations. A small 

amount of flow is lost when backwater from the Peace River 

flows up the 0.5-mi inactive spring run and floods the remnant 

spring pool of Kissengen Spring. During the 1960s, a large 

clay plug was placed in Kissengen Spring to limit flow 

exchange (Jackson, 2008). Currently (2009), flows travel up 

the inactive spring run and are scouring out a new channel 

to Otter Sink where observed streamflow losses to this sink 

are about 2 to 3 ft3/s (Charles Cook, FDEP, written commun., 

2009).

 Located in the floodplain about 800 ft east of Kissengen 

Spring and 400 ft west of Peace River, Tom’s Sink was 

discovered through aerial photo examination in 2008 (Tom 

Jackson, written commun., 2008). The aerial photo indicates 

that the flow to this sink has eroded an approximate 300-ftlong distributary, extending from the sinkhole to the relict 

Kissengen Spring run channel. During July 2008, flow was 

observed draining into Tom’s Sink (Charles Cook, FDEP, 

written commun., 2008). Flow losses to these high-water 
64 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Peace River

Crevasses Sink

Paternoster

Complex

Log Sink

Dover Sink

Liz Sink

Gator Sink

±

Elevation, in feet above NGVD 1929

68 to 70

(A)

(B) EXPLANATION

0 200 400 Feet

0 50 100 Meters

0 50 100 Feet

0 10 20 Meters

Dover Sink

>70 to 72

>72 to 74

>74 to 76

>76 to 78

>78 to 80

>80 to 82

>82 to 84

>84 to 86

±

Images from U.S. Geological Survey digital orthophoto quadrangle data, photographed in 2004

Universal Transverse Mercator Projection, Zone 17

Figure 40. (A) Elevation of sinks and riverbed 

channel along the lower end of Reach 2, and 

(B) detailed view of Dover Sink.
Streamflow 65

(A) Exposed rocks, 2002 (B) Sediment and fish accumulation, 2006

(C) Storm event at Dover Sink, 2006

Photo credit: Lari Knochenmus, USGS

(E) Infilling and scouring at Dover Sink, 2008

Photo credit: Charles Cook, FDEP

(D) Continued scouring of Dover Sink Distributary channel, 2007

(F) Dover Sink ponded, 2008

Photo credit: P. A. Metz, USGS Photo credit: Charles Cook, FDEP

Photo credit: P. A. Metz, USGS

Photo credit: P. A. Metz, USGS

Photo credit: P. A. Metz, USGS

Figure 41. Changing hydrologic conditions at Dover Sink.
66 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

Figure 42. Topographical profile of Peace River channel and Dover Sink Distributary.

Figure 43. (A) Inflow to Dover Sink Distributary from two sources—from Peace River flowing south and Sixmile Creek flowing north—

and (B) comparison of discharge from Peace River at Clear Springs and Sixmile Creek (location of gages shown in fig. 13). 

90

85

80

75

70

65

0 500 1,000 1,500 2,000 2,300

Crevasses Sink

Dover Sink 68.9 FT

DISTANCE ALONG SURVEYED CHANNEL ELEVATION PROFILE, IN FEET

84.3 FT Water-surface elevation required in channel

to continue flow downstream

Confluence of Peace River

channel and Dover Sink Distributary Dover Sink Distributary

ELEVATION, IN FEET ABOVE NGVD 1929

FLOW

NORTH SOUTH

Land-surface elevation

survey points

82.2 FT

Peace River channel

Oct Nov Dec

2007

Jan Feb Mar Apr May June July Aug Sept

90

80

70

60

50

40

30

20

10

0

-10

Peace River at Clear Springs

Sixmile Creek

(B)

DISCHARGE IN CUBIC FEET PER SECOND

When discharge is low,

inflow from Sixmile Creek will flow

upstream to Dover Sink

Peace River

2006

(A)

Peace River

Flow from

downstream

Sixmile Creek

Dover Sink

Distributary

Photo credit: Charles Cook, FDEP

Figure 43 . Photograph of inflow to Dover Sink Distributary from two directions--from Peace River flowing south and

from Sixmile Creek flowing north and comparison of discharge from Peace River at Clear Springs and Sixmile Creek.

(A)

(B)
Streamflow 67

channel sinks are currently unknown. Both Otter Sink and 

Tom’s Sink recharge the underlying aquifer during periods of 

floodplain inundation, and probably influence water levels in 

the Kissengen Spring area LW4P monitor wells (fig. 13B).

Effects of Groundwater Conditions on 

Streamflow Losses 

Within the upper Peace River karst area, streamflow 

losses are dependent on a number of hydrologic conditions. 

The elevations of the potentiometric surfaces of the intermediate aquifer system and the Upper Floridan aquifer are 

two of the most important factors that influence streamflow 

losses along the upper Peace River. As water-level differences 

increase between aquifer units during dry periods because of 

pumpage or hydrologic stresses, water stored in the intermediate aquifer system drains downward into the Upper Floridan 

aquifer. This in turn creates a potential for river water to drain 

into empty void spaces or cavities in the intermediate aquifer 

system. During these low-water periods, the small amount of 

water in the stream channel can be observed flowing into the 

various sinks until the upper reaches of the river become dry. 

During high-water periods, as water-level differences decrease 

between the river and the underlying aquifers and the storage 

in the aquifers is replenished, the potential for streamflow 

losses declines.

To understand these processes, analyses were made 

to determine if streamflow losses were proportional to the 

decline in the potentiometric surface below the elevation of 

the riverbed. Groundwater conditions were analyzed separately for Reaches 1 and 2 because of the different hydrologic 

conditions that exist in these reaches. For Reach 1, groundwater conditions were defined as the vertical distance of the 

potentiometric surface below the riverbed elevation, using 

water levels from the Upper Floridan aquifer and the intermediate aquifer system measured at the LW1P site. Because 

groundwater-level data were absent during much of the study 

period near Reaches 1 and 2, data from the ROMP 59 Avon 

Park and Hawthorn wells were used to extrapolate water-level 

conditions as necessary. For Reach 2, groundwater conditions 

were defined using only the Upper Floridan aquifer (LW3P), 

because the Upper Floridan aquifer and the intermediate 

aquifer system are hydraulically connected along this reach. 

Streamflow losses were calculated from discharge 

measurements made during the study period at the three 

upstream gaging stations that spanned Reaches 1 and 2 

(sites 1, 7, and 11; fig. 22). Discharge measurements selected 

for this analysis included synoptic seepage run measurements 

made between these stations during baseflow conditions. 

Under certain circumstances, continuous daily discharge data 

could be used for this analysis, but much of the continuous 

record is complicated by effects of overbank storage, rainfall 

and surface inflows, and zero-flow days. The continuous 

record was only used to determine streamflow losses when 

these complicating factors were not observed. 

DIFFERENCE BETWEEN THE ELEVATION OF THE RIVER BOTTOM

AND THE HEADS IN THE UPPER FLORIDAN AQUIFER (LW3P), IN FEET

(C)

y = -0.5655x - 6.1665

r = 0.27 2

-35

-30

-25

-20

-15

-10

-5

0 -505101520253035

REACH 2

STREAMFLOW LOSS, IN CUBIC FEET PER SECOND

DIFFERENCE BETWEEN THE ELEVATION OF THE RIVER BOTTOM

AND THE HEADS IN THE UPPER FLORIDAN AQUIFER (LW1P), IN FEET

(B)

y = -0.8386x - 7.4101

r = 0.81 2

-35

-30

-25

-20

-15

-10

-5

0 -505101520253035

REACH 1

STREAMFLOW LOSS, IN CUBIC FEET PER SECOND

DIFFERENCE BETWEEN THE ELEVATION OF THE RIVER BOTTOM AND

THE HEADS IN THE INTERMEDIATE AQUIFER SYSTEM (LW1P), IN FEET

(A)

y = -0.1582x - 3.0984

r = 0.94 2

-35

-30

-25

-20

-15

-10

-5

0 -505101520253035

REACH 1

STREAMFLOW LOSS, IN CUBIC FEET PER SECOND

Figure 44. Relation of streamflow losses to aquifer water 

levels in Reaches 1 and 2 during seepage measurements.
68 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

In Reach 1, the intermediate aquifer system is hydraulically connected to the river and streamflow losses during 

baseflow conditions were strongly correlated to water-level 

changes in this aquifer (r2 = 0.94; fig. 44A). During the 

dry season when groundwater levels were at their lowest, 

the water-level difference between the elevation of the 

riverbed and the intermediate aquifer system was 14.5 ft, and 

streamflow losses were greatest (-20 ft3/s). During the wet 

season when water levels in the intermediate aquifer system 

were at their highest level, there was a reduced potential for 

streamflow losses. During these increased water-level periods, 

streamflow gains were noted in the river. 

 In Reach 1, there also was a good relation between 

streamflow losses and the vertical distance between the 

riverbed elevation and the potentiometric surface of the 

Upper Floridan aquifer during seepage runs (r2 = 0.81; 

fig. 44B). This relation reflects the influence that the Upper 

Floridan aquifer has on the intermediate aquifer system. 

As water levels decline in the Upper Floridan aquifer because 

of pumpage or hydrologic stresses, these declines affect water 

levels in the intermediate aquifer system and, consequently, 

influence streamflow losses. 

In Reach 2, there was not a significant linear relation 

between streamflow losses and the vertical distance between 

the riverbed and the Upper Floridan aquifer levels during 

seepage runs (r2 = 0.27; fig. 44C). In Reach 2, the relation 

between streamflow losses and aquifer level declines is more 

complex. In this reach, the upper Peace River is connected to 

both the intermediate aquifer system and the Upper Floridan 

aquifer through a large conduit system. Because this conduit 

system is very large, it can accommodate a large proportion of 

flow from the river at multiple river stages.

Groundwater Flow Patterns Surrounding the 

Upper Peace River

The groundwater flow patterns surrounding the upper 

Peace River are influenced by recharge conditions, inflow 

from the river, and regional groundwater withdrawals. Water 

levels collected from a network of wells, sinks, tributaries, and 

phosphate-mine outfalls along an approximate 5-mi reach of 

the upper Peace River provide the basis for relating groundwater flow patterns to streamflow losses along the upper Peace 

River. To help define groundwater flow patterns, continuous 

water-level data were collected from a network of two surficial 

aquifer wells, four intermediate aquifer system wells, three 

Upper Floridan aquifer wells, and two major sinks (Gator and 

Dover Sinks) (fig. 13B). A well nest was installed at each of 

the geologic core sites (LW1P, LW3P, and LW4P) to determine 

the vertical component of flow within an aquifer or between 

aquifer units (fig. 13B). 

Groundwater data were collected by the USGS at the 

LW1P well nest site from May 2005 to September 2007 and at 

the LW3P and LW4P well nest sites from July 2006 through 

September 2007. Supplemental groundwater data also were 

obtained from the SWFWMD, who continued monitoring 

at these sites after September 2007. Table 5 lists the index 

number for each well, location by latitude and longitude (ID 

number), well name, well depth and cased interval, hydrogeologic unit, and the summary of data collected at each well. 

Because well nests near the river were not installed until 

later in the study, data from the ROMP 59 Avon Park and 

Hawthorn wells were used to help determine current and longterm trends in the study area (table 5, figs. 13 and 45). Linear 

regression analyses show a significant correlation between 

water levels in Upper Floridan aquifer wells at the study sites 

(LW1P, LW3P, and LW4P) and ROMP 59 Avon Park well 

(fig. 45). Based on the record at the ROMP 59 Avon Park 

well (1997-2007 water years), groundwater levels collected at 

LW1P from April 2005 through March 2006 were considered 

above average (high-water analysis period; fig 45) whereas 

water levels for the 2007 water year were considered below 

average (low-water analysis period; fig. 45).

Hydrographs that show the relations between water 

levels in the river; the underlying aquifers at LW1P, LW3P, 

and LW4P monitoring sites; and Dover Sink are shown in 

figure 46A-F. Comparison between water levels in the upper 

and lower aquifers within the intermediate aquifer system 

show that the hydraulic connection between (and within) 

these units varies between locations. Three wells were 

completed in the upper Arcadia aquifer (LW1P IAS UA, 

LW3P IAS UA, and LW4P IAS UA), and one well was 

completed in the lower Arcadia aquifer (LW3P IAS LA, 

fig. 46A). Water-level comparisons between sites for the 

upper Arcadia aquifer (LW1P IAS UA and LW3P IAS UA) 

showed good agreement (r2 = 0.73; fig. 46A). Water-levels 

in the lower Arcadia aquifer at the LW3P well site (LW3P 

IAS LA) and upper Arcadia aquifer at the LW4P well 

site (LW4P IAS UA) were strongly correlated (r2 = 0.98; 

fig. 46A), indicating a strong hydraulic connection between 

aquifers. Comparison between the upper and lower Arcadia 

aquifer levels at the LW3P well site (LW3P IAS UA and 

LW3P IAS LA) indicated a good connection (r2 = 0.73; 

fig. 46A), although not as strong as the other sites.

Variable relations between aquifers within the 

intermediate aquifer system and between well sites indicate 

the complexity of the geology in the intermediate aquifer 

system. The intermediate aquifer system contains interbedded 

carbonates and siliciclastic sediments that contribute to the 

heterogeneity of this unit, and localized differences in groundwater levels. In addition, the Arcadia Formation contains 

weathered dolomite that is fractured and has pinpoint vugs, 

voids, and numerous fossils casts and molds that aid in the 

development of secondary porosity. This porosity strengthens 

the hydraulic connection between these aquifers (fig. 14). 

Although the confining units of the intermediate aquifer 

system impede downward flow into the Upper Floridan 

aquifer, the hydraulic connection between aquifers increases 

when the confining units are thinner, more permeable, 

breached by sinkholes, and contain sand-filled piping features,

or cavities and conduit systems. 
Streamflow 69

Table 5. Characteristics and data summary for wells and sinks located along the upper Peace River.

[BLS, below land surface; SWFWMD, Southwest Florida Water Management District; HTRN, Hawthorn; IAS, intermediate aquifer system; LA, lower Arcadia 

aquifer; LH, Lower Hawthorn, No.; number; NRSD, nonartesian sand aquifer; SA, surficial aquifer; SUW and SWNN, Suwannee; UA, upper Arcadia aquifer; 

UFA, Upper Floridan aquifer; UH, Upper Hawthorn; CON, continuous; REC, recorder; QW, water quality; –, no data]

Index 

No.1

 USGS 

identification

No.

SWFWMD

well or sink name2

USGS

 abbreviated name

Hydrogeologic 

unit

Total 

depth BLS 

(feet)

Total cased 

interval 

BLS

(feet)

Diameter, 

(inches) Data summary

1 275336081484401 LW1P UFA WWTP-LW1P SWNN UFA 235 95 6 CON REC, QW

2 275336081484402 LW1P IAS UA WWTP-LW1P HTRN IAS (UA) 75 18 6 CON REC, QW

3 275336081484403 LW1P SA WWTP-LW1P NRSD SA 6 2 6 CON REC, QW

4 275156081481901 LW3P UFA Clear Springs SUW UFA 320 170 6 CON REC, QW

5 275156081481902 LW3P IAS LA Clear Springs LH IAS (LA) 140 67 6 CON REC, QW

6 275156081481903 LW3P IAS UA Clear Springs UH IAS (UA) 37 21 6 CON REC, QW

7 275156081481904 LW3P SA Clear Springs SA SA 12 2 6 CON REC, QW

8 275034081483901 LW4P UFA Kissengen Spring SUW UFA 310 151 6 CON REC, QW

9 275034081483902 LW4P UA Kissengen Spring UH IAS (UA) 76 31 6 CON REC, QW

10 275220081480101 Clear Springs IAS Clear Springs IAS IAS (LA) 143 62 6 CON REC, QW

11 275314081514201 ROMP 59 AP ROMP 59 Avon Park UFA 1,050 200 12 CON REC

12 275314081514202 ROMP 59 HTRN ROMP 59 HTRN IAS 142 122 6 CON REC

13 274908081480901 Homeland No. 4 Homeland No. 4 IAS (LA) 202 56 24 CON REC

14 274841081480901 Homeland No. 9 Homeland No. 9 UFA 746 – 6 CON REC

15 275226081481900 Gator Sink Gator Sink IAS (LA) – – – CON REC

16 02294705 Dover Sink Peace River Distributary

 at Dover Sink

IAS (LA) – – – CON REC, QW

1

Index numbers refer to wells and sinks shown in fig. 13B.

2

Well name used in this study.

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

90

80

70

60

50

40

30

20

Highest level of 85.92 feet above NGVD 1929 on October 15, 2004

(85.92 ft is the highest level for the 1977-2007 period of record)

Average (ROMP 59 Avon Park)

for the1997 to 2007

67.2 ft above NGVD 1929

WATER YEARS

r

2

Lowest level of 36.16 feet above NGVD 1929 on

June 10, 2000 (33.33 ft. is the lowest level for the

1977-2007 period of record on May 16, 1981)

High-water

analysis

period

Low-water

analysis

period

WATER LEVEL, IN FEET ABOVE NGVD 1929

LW1P UFA r = 0.99

LW3P UFA r = 0.97

LW4P UFA r = 1.00

ROMP 59 AVON PARK

Coefficient of determination for

relations between Upper Floridan

aquifer water levels in ROMP 59

and study wells

2

2

2

1997

Figure 45. Long-term hydrograph for ROMP 59 Avon Park Upper Floridan aquifer well and hydrographs for the study period 

for Upper Floridan aquifer wells at LW1P, LW3P, and LW4P monitor sites (location of wells shown in figs. 8 and 13B).
70 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

EXPLANATION

100

95

90

85

80

75

70

65

60

WATER LEVEL, IN FEET ABOVE NGVD 1929

J

2005 2006

LW1P SA, dry when flatlined

LW1P IAS UA

LW1P UFA

LW1P WELL SITE Peace River

2007

LW1P WELL SITE LW1P dry when flatlined SA,

LW1P IAS UA

LW1P UFA

Peace River

2006

LW3P SA

LW3P IAS UA

LW3P IAS LA

LW3P UFA

Peace River,

dry when flatlined

LW4P UFA

LW4P WELL SITE

LW4P IAS UA

LW3P WELL SITE Peace River

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

100

95

90

85

80

75

70

65

60

90

85

80

75

70

65

60

55

50

95

90

85

80

75

70

65

60

55

2006 2007 2006 2007

r LW3P IAS LA and UFA = 1.00 2 LW3P

r LW3P IAS UA and LW3P UFA = 0.82 2

r Peace River and SA = 0.94 2 LW1P

r Peace River and LW1P IAS UA = 0.96

r Peace River and LW1P UFA = 0.22

r LW1P SA and LW1P IAS UA = 0.98

r LW1P IAS UA and LW1P UFA = 0.22

2

2

2

2

r IAS UA and UFA = 0.97 2 LW4P LW4P

r IAS UA and UFA = 0.62 2 LW1P LW1P

r Peace River and LW1P UFA = 0.45 2

95

90

85

80

75

70

65

60

55

2006 2007

r LW3P IAS UA and LW1P = 0.73 2 IAS UA

r LW3P IAS UA and LW3P IAS LA = 0.73

r LW3P IAS LA and LW4P IAS UA = 0.98

2

2

90

85

80

75

70

65

60

55

50 O

2006 2007

N D J F M A M J J A S

r LW3P UFA and = 0.87 2 Dover Sink

r LW3P UFA and LW1P UFA = 0.98

r LW3P UFA and LW4P UFA = 0.98

r LW1P UFA and LW4P UFA = 0.99

2

2

2

LW3P IAS UA

LW3P IAS LA

LW4P IAS UA

LW1P IAS UA

LW1P UFA

LW3P UFA

LW4P UFA

DOVER SINK,

dry when flatlined

Periods when recharge waters

from Dover sink augment

the water levels near

LW3P UFA well

r

2 COEFFICIENT OF DETERMINATION BETWEEN

WATER LEVELS (all regressions significant to

alpha level of 0.05)

UFA

SA

IAS

UPPER FLORIDAN AQUIFER

SURFICIAL AQUIFER

INTERMEDIATE AQUIFER SYSTEM

UPPER ARCADIA AQUIFER

LOWER ARCADIA AQUIFER

UA

LA

(A) (B)

(C) (D)

(E) (F)

High-water analysis period Low-water analysis period

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

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

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

Figure 46. Comparison of the Peace River stage and water levels in monitor wells completed at different depths in the 

intermediate aquifer system and Upper Floridan aquifer (location of wells are shown in fig. 13B and well depths and cased 

intervals are shown in table 5).
Streamflow 71

A comparison of water levels in the three Upper Floridan 

aquifer wells (LW1P UFA, LW3P UFA, and LW4P UFA) 

indicated significant relations between all well sites (r2 = 0.98-

0.99; fig. 46B). The significant relations between these well 

sites indicate a good lateral connection and the regional nature 

of this unit. The lateral head gradient in the Upper Floridan 

aquifer decreases from north (LW1P) to south (LW4P), at 

about 0.70 foot per mile (ft/mi). 

The differences between the elevation of the river bottom 

and water levels in the underlying aquifers were greatest during 

the dry season (May through June). The largest daily difference 

between the river bottom elevation and the Upper Floridan 

aquifer water levels occurred on June 1, 2007, with differences 

of 26.34 ft at well LW1P, 25.38 ft at well LW3P, and 26.01 ft 

at well LW4P. Substantial streamflow losses occur at the end 

of the dry season, when large volumes of water are often 

required to replenish the underlying storage of the intermediate 

aquifer system and Upper Floridan aquifer. At the three well 

sites, recharge conditions existed for most of the study period 

(fig. 12). An exception to this overall pattern occurred at the 

LW1P site when intermediate aquifer system levels were higher 

than surficial aquifer levels for a brief period in 2005.

The water-level differences at the well sites and linear 

relations between aquifers yield insight into the degree of 

confinement or interconnection between the intermediate 

aquifer system and the Upper Floridan aquifer. Differences 

between these water levels may indicate the localized nature 

of the confining unit sediments or the influence of karst 

features. For example, permeable sediments or secondary 

porosity associated with a karst environment will enhance the 

downward movement of recharge waters, resulting in a smaller 

water-level difference between aquifers. 

At both LW3P and LW4P well sites (2007 water year) 

a strong connection exists between the intermediate aquifer 

system and Upper Floridan aquifer, as indicated by significant 

linear relations between water levels (r2 = 1.00 for LW3P wells 

and r2 = 0.97 for LW4P wells; fig. 46C-D). In addition, the 

smaller average water-level differences between the intermediate aquifer system and Upper Floridan aquifer at these sites 

(0.67 ft for LW3P wells, and 6.0 ft for LW4P wells) indicate a 

better hydraulic connection between aquifer units. The LW3P 

well site is in an area where prominent karst features (Dover 

Sink and Gator Sink) are located (fig. 13B), which is evidence 

of the cavernous karst conduit system that facilitates water 

movement between the aquifer units. The LW4P well site also 

is in an area where an extensive cavernous system exists that 

is associated with the dry Kissengen Spring.

In contrast, there is less connection between the intermediate aquifer system and Upper Floridan aquifer at the LW1P 

well site (2007 water year), as indicated by a weaker relation 

between water levels (r2 = 0.62; fig. 46F). This relation may 

indicate there is more confinement at this site, which limits 

the connection between the intermediate aquifer system and 

Upper Floridan aquifer. Geologic cores and aquifer tests 

analyzed during the study indicate that a thick, low permeability layer exists between the two aquifers at the LW1P site. 

In addition, a relatively large average water-level difference 

(15 ft) between the intermediate aquifer system and the Upper 

Floridan aquifer was noted at this site, which indicates more 

confinement. 

During above-average water-level conditions (high-water 

analysis period, April 26, 2005 to March 2, 2006; fig. 46E), 

the aquifers at the LW1P well site show different relations 

between one another and the river compared to below-average 

water-level conditions (low-water analysis period, October 1, 

2006 to September 30, 2007; fig. 46F). During the high-water 

analysis period, there were significant relations between river 

levels and the surficial aquifer (r2 = 0.94), between the river 

levels and the upper Arcadia aquifer (r2 = 0.96), and between 

the upper Arcadia aquifer and surficial aquifer (r2 = 0.98). 

The average river stage for this time period was 1.6 ft higher 

than surficial aquifer levels, indicating lateral recharge to that 

aquifer. The hydraulic connection between the river, surficial 

aquifer, and upper Arcadia aquifer can be attributed to the 

widespread karstified geologic framework of the Arcadia 

Formation. Geologic cores from the LW1P well indicate that 

the Arcadia Formation contains sections of fractured dolomite 

at depths ranging from 16 to 26 ft and from 50 to 75 ft, which 

enhance the hydraulic connection between the river, the 

surficial aquifer, and the intermediate aquifer system. 

As water-level differences increase between units, there 

is an increased potential for downward recharge from the 

overlying hydrologic units at the LW1P site. During highwater analysis period (fig. 46E), there were no significant 

relations between river stage and the Upper Floridan aquifer 

(r2 = 0.22), and between the intermediate aquifer system 

and Upper Floridan aquifer (r2 = 0.22) at the LW1P well 

site. In contrast, statistical relations indicate an increased 

potential for downward flow during the low-water analysis 

period (fig. 46F). During this time, water-level relations 

between the river stage and the Upper Floridan aquifer 

improved slightly (r2 = 0.45) compared to the high-water 

period (r2= 0.22). Relations also improved between the 

intermediate aquifer system and the Upper Floridan aquifer 

at LW1P during the low-water period (r2 = 0.62) compared to 

the high-water period (r2= 0.22), indicating a higher degree of 

interconnection during low-water periods. 

Flow Patterns Derived from Chemical 

Constituents and Isotopic Tracers

Information on groundwater flow patterns along the 

upper Peace River also can be derived using chemical and 

isotope-tracing methods. Water quality in the river is influenced by rainfall, groundwater and surface-water inflows, and 

land-use practices. Water quality in the underlying aquifers is 

controlled by the lithology and mineralogy of the particular 

unit, residence time of water in contact with the aquifer 

matrix, and recharge from the overlying aquifer and the 

river. These variations in water chemistry between the river, 

the intermediate aquifer system, and Upper Floridan aquifer 
72 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

provided insight into the multiple flow processes occurring 

along the upper Peace River. Stiff diagrams of water-chemistry 

data collected during this study show the variability of water 

in the river and the two aquifers (fig. 47).

 River samples collected north of Sixmile Creek, 

Phosphate Mine Outfall CS-8, and Barber Branch had 

lower concentrations of dissolved constituents than water 

collected downstream from these mine-outfall sites (fig. 13B). 

As discussed in previous sections, the study area is lined by 

clay-settling ponds and mine-outfall sites, and water samples 

collected during this study varied chemically depending on 

their proximity to these sites. A river sample was collected at 

the Dover Sink Distributary during a low-flow period (mean 

discharge of 14 ft3/s at Peace River at Bartow on March 

23, 2007) when inflows to the upper Peace River were only 

derived from Peace Creek Drainage Canal. During this time, 

the remaining flow from the upper Peace River drained into 

Dover Sink. The Stiff diagram of the Dover Sink Distributary 

indicates that the water was slightly enriched in sodium, potassium, chloride, and bicarbonate, and was not influenced by 

mine drainage (fig. 47). The river-water sample was characterized by a high color content, and the specific conductance and 

pH were 397 microsiemens per centimeter (μS/cm) and 7.4, 

respectively. 

Water samples collected downstream from the Peace 

River below Sixmile Creek are influenced by mine outfalls. 

During low-flow conditions, the mine outfalls are the primary 

source of inflows to this reach of the river. A surface-water 

sample collected downstream from Barber Branch had a higher 

ionic-strength than the upstream Dover Sink Distributary site. 

The water in this section of the river was influenced by the mine 

outfalls of Sixmile Creek, Phosphate Mine Outfall CS-8, and 

Barber Branch. Measured specific conductance and pH values 

were 690 μS/cm and 7.9, respectively. River water downstream 

from Barber Branch contained significantly higher concentrations of calcium, sulfate, and magnesium than water collected at 

Dover Sink Distributary (fig. 47). When river water flows north 

from Sixmile Creek and drains into Dover Sink, this inflow 

water is more enriched in calcium, sulfate, and magnesium than 

inflow water from Peace Creek Drainage Canal.

Stiff diagrams also show the variability in chemical 

constituents between the intermediate aquifer system and the 

Upper Floridan aquifer. The water chemistry of the intermediate aquifer system and the Upper Floridan aquifer was 

dominated by calcium carbonate. In addition, the intermediate 

aquifer system had increased concentrations of magnesium 

due to the dissolution of dolomite in the carbonate aquifer. 

Both aquifers contain water that is predominantly a calciumbicarbonate water type, but the intermediate aquifer system 

contains water with higher concentrations, on average, of 

sulfate, potassium, bicarbonate, and chloride than water in the 

underlying Upper Floridan aquifer. In some cases, the upper 

Arcadia aquifer contained water with higher concentrations 

of calcium, bicarbonate, and sulfate than water in the lower 

Arcadia aquifer.

Surface Water

2007

Ground Water

2007

Kissengen Spring

Clear Springs IAS well

(lower Arcadia aquifer)

LW1P IAS UA well

LW4P IAS UA well

Homeland 4 well

(lower Arcadia aquifer)

LW1P UFA well

LW4P UFA well

LW3P IAS UA well

LW3P IAS LA well

LW3P UFA well

INTERMEDIATE

AQUIFER SYSTEM

(IAS)

UPPER FLORIDAN

AQUIFER (UFA)

Spring Water

1959

Peace River below Barber Branch gaging station

Cations Anions

10 5 5 10

Chloride

Calcium

Sodium and Potassium

Sulfate

Bicarbonate

Magnesium

Milliequivalents per liter

Dover Sink Distributary

Figure 47. Stiff diagrams for surface-water and groundwater 

sites along the upper Peace River (location of sampling sites are 

shown in fig. 13B and well depths and cased intervals are shown 

in table 5).
Streamflow 73

River and spring flow are influenced by groundwater conditions. 

Stages of riverflow, from flowing to dry (top and bottom); and 

mud puddle at inactive Kissengen Spring (center).

Photo credit: P.A. Metz, USGS

Streamflow 73
74 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

 There are several reasons for the chemical enrichment of 

the shallower part of the intermediate aquifer system: (1) the 

study wells are located in areas where the surficial aquifer 

is thin or absent and recharge waters have been affected by 

mining practices; (2) the wells are located in an area where 

there is extensive karst development that provides preferential 

recharge pathways from the surface to the underlying aquifer; 

and (3) the wells are located near mine-outfall pits that 

breach the upper confining layers. Some or all of these factors 

may influence the water chemistry of the intermediate aquifer 

system within the study area. 

One of the wells sampled from the intermediate aquifer 

system (Homeland No. 4 well; 650 ft west of Peace River) is 

located in an area that has previously been mined (near several 

dredged pit lakes) but away from extensive karst development 

(fig. 13A). A Stiff diagram for this well indicates that the water 

is a calcium-bicarbonate type, but with lower levels of sulfate, 

magnesium, potassium, and chloride than wells closer to the 

river (fig. 47). This well is deeper (202 ft; table 5) than any of 

the other intermediate aquifer system wells sampled during 

this study, which also may explain the reduced influence of 

water from the mined areas.

Stiff diagrams of the three water samples collected from 

the Upper Floridan aquifer show similar chemical patterns. 

However, water samples at the LW4P UFA well had slightly 

higher magnesium and bicarbonate concentrations than 

samples from the other Upper Floridan aquifer wells, indicative of the chemical influence of water from the intermediate 

aquifer system (fig. 47). Hydrologic data, aquifer tests, and 

geophysical logs indicate a strong connection between the 

intermediate aquifer system and the Upper Floridan aquifer 

in this area, and the chemical data validates the downward 

movement of this water. For the LW3P well site, waters from 

the intermediate aquifer system (LW3P IAS LA) and the 

Upper Floridan aquifer (LW3P UFA) show almost identical 

chemical signatures, indicative of a strong hydrologic connection between these sites. The relation between water levels in 

these two wells corroborates the strong hydrologic connection 

between aquifers (r2= 1.00).

 A Stiff diagram also was constructed from historical 

water-quality data collected at Kissengen Spring in 1959, and 

is considered to represent the groundwater flow patterns in 

the study area under discharging conditions. A water sample 

was collected when the spring flow was measured at 9 ft3/s, 

just before the spring ceased to flow in 1960 (Stewart, 1961). 

The chemical signature of the spring water indicates a chemical 

pattern similar to that of the water collected from the wells 

tapping the Upper Floridan aquifer and the lower Arcadia 

aquifer (fig. 47). 

The naturally occurring stable isotopes deuterium and 

oxygen-18 also were measured in water samples collected 

from the river and seven wells in the study area to help determine flow paths between the river and the underlying aquifers. 

Differences in the enrichment of the isotopes by evaporation 

can give an indication of the water pathway. For example, 

river water derived from surface inflows has more opportunity 

to evaporate than does groundwater; therefore, the river water 

will have a heavier signature (larger δ value) than groundwater. The samples were collected during March 23-26, 2007 

when groundwater levels were declining and sink features 

were draining the river water to the underlying aquifers. 

During this sampling, upper Peace River flow ended at Dover 

Sink and the estimated discharge to the sink was about 2 ft3/s. 

There was little isotopic variability between samples 

from the LW3P UFA, Clear Springs IAS, and LW1P 

UFA wells (fig. 48A), which may indicate that recharge 

waters in these areas were from a similar source and that the 

underlying aquifers are affected by the same flow processes 

(fig. 48A). Although isotopic samples were not collected at a 

surface-water site near the LW1P well, the isotopic composition would probably be similar to that of samples from Dover 

Sink Distributary because of the close proximity of the well 

and distributary (3.0 mi) and the short amount of time required 

for a particle of water to travel (less than 1 day) from the well 

to the distributary.

The percentage of river water in groundwater was used 

to help determine flow paths to the underlying aquifers. The 

percentage of river water (x) in the groundwater near the river 

was calculated using d18O as the conservative tracer in the 

following equation: 

 x = ( δgw – δmw ) / ( δrw – δmw ), (2)

where δ is the oxygen-18 value for the groundwater sample 

(gw), meteoric water (mw), and river water (rw). The d18O 

for river water used in the calculations was from Dover Sink 

Distributary (Peace River), and is assumed to be representative of river water recharging the groundwater. The meteoric 

water end member is water uninfluenced by recharge from the 

river. Several meteoric end members were considered in the 

calculations: (1) volume-weighted mean d18O of rainwater at a 

site in Polk County (Sacks, 2002); (2) water from the intermediate aquifer system unaffected by river recharge (ROMP 45 

Hawthorn; Sacks and Tihansky, 1996); and (3) water from the 

Upper Floridan aquifer unaffected by river recharge (ROMP 45 

Suwannee; Sacks and Tihansky, 1996). 

Results for the end member analysis using the rainwater 

and the intermediate aquifer system water were similar, 

showing little variability (average difference less than 

1 percent). A separate meteoric water end member analysis 

was conducted for the Upper Floridan aquifer, because 

groundwater in this area was recharged thousands of years 

ago, under different climatic conditions, and can have naturally elevated d18O values (Plummer and Sprinkle, 2001). 

Therefore, the meteoric water end member for Upper Floridan 

aquifer samples influenced by Peace River recharge could 

be a mix of this older groundwater and recent recharge. 

However, because of the current recharge setting, the deeper 

groundwater was not considered to influence water from the 

intermediate aquifer system. 
Streamflow 75

wells. The lowest fraction (38 percent) of recharge water from 

the Dover Sink was LW3P IAS UA (upper Arcadia aquifer). 

This well is only completed to 37 ft and indicates that Dover 

Sink is not as well connected to a shallow part of the aquifer.

 For Upper Floridan aquifer water, the percentage of river 

water ranged from 52 to 89 percent, using the old groundwater 

meteoric end member, and from 77 to 98 percent, using the 

recent rainwater meteoric end member. Regardless of the 

meteoric water end member, the river water is distinctly identifiable in the deeper aquifer. Samples from LW3P UFA and 

LW1P UFA contained the highest percentage of river water of 

all samples (98 to 94 percent, respectively; fig. 48B).

Influence of Large Karst Features on Flow 

Patterns and Streamflow Losses

An important characteristic of the geology underlying 

the upper Peace River is the capacity to store large volumes 

of water in the underground cavities within the floodplain and 

surrounding area. The geology of this area is highly karstified, 

as evidenced by numerous karst features and fractured carbonates and cavernous zones identified in geologic cores and 

aquifer tests. Geologic logs, aquifer and dye tests, and video 

logs indicate that there are several layers within the floodplain 

geology that are cavernous, highly transmissive, and have the 

ability to transport large volumes of water at a rapid rate. The 

following hydrograph analysis illustrates how karst features 

provide the hydrologic connection between the river and the 

underlying aquifers.

 Water levels at two sinks (Gator Sink and Dover Sink; 

fig. 36), located in the floodplain of the highly karstic region 

of Reach 2, were monitored to determine how these features 

influence groundwater flow patterns. Dover Sink is the most 

influential karst feature within the upper Peace River karst 

area, and accounts for the most streamflow losses from the 

river. Gator Sink is less influential than Dover Sink in terms of 

streamflow losses, but accepts river flow during high stages. 

Gator Sink also receives groundwater flow from localized 

floodplain storage during low-flow conditions that travels 

through Ledges Sink and the Catacombs Complex. 

A hydrograph of Clear Springs IAS well shows the 

simultaneous response of the intermediate aquifer system 

to recharge through Dover Sink (fig. 49A-B). This well 

is located 500 ft east of Dover Sink and is 143 ft deep, 

cased to 62 ft. Water levels in the sink and well are highly 

correlated (r2 = 0.94, fig. 49A), indicating a good hydraulic 

connection between the two sites that is consistent with the 

fractured karst hydrology of the upper Peace River karst area. 

Prolonged dry periods deplete much of the water stored within 

the cavernous system that underlies the upper Peace River. 

Recharge waters rapidly fill the cavities through localized 

sinks when rainfall occurs.

Geophysical well logs and slug tests performed at the 

nearby LW3P IAS LA well indicate that the Clear Springs IAS 

well is open to geologic sections that are highly transmissive. 

[ IAS, intermediate aquifer system; LA, lower Arcadia aquifer;

UA, upper Arcadia aquifer; UFA; Upper Floridan aquifer]

Estimated error in measurement

is + or - 5 percent

DOVER SINK DISTRIBUTARY WATER IN THE GROUNDWATER,

BASED ON DELTA OXYGEN-18, IN PERCENT

LW4P

UFA

LW4P

IAS UA

CLEAR

SPRINGS

IAS

LW3P

UFA

LW1P

UFA

LW1P

IAS UA

LW3P

IAS UA

(A)

(B)

DELTA DEUTERIUM, IN PER MIL

DELTA OXYGEN-18, IN PER MIL

10

5

0

-5

-10

-15

-20

-4

LW1P IAS UA LW1P UFA

LW3P IAS UA

LW3P UFA

LW4P IAS UA

LW4P UFA

LOCAL METEORIC WATER LINE (Sacks, 2002)

LOCAL EVAPORATION TREND LINE (Sacks, 2002)

GROUNDWATER SAMPLE

SURFACE-WATER SAMPLE

EXPLANATION

Clear Spring IAS well

Peace River at Dover Sink Distributary

-3 -2 -1 0 1

100

90

80

70

60

50

40

30

20

10

0

Figure 48. (A) Delta deuterium in relation to delta oxygen-18 in 

Peace River surface water and groundwater at selected well 

sites and (B) the percentage of river water in groundwater using 

delta oxygen-18 (location of sampling sites are shown in fig. 13B, 

and well depths and cased intervals are shown in table 5).

Results of this analysis indicate that the percentage of 

river water in the intermediate aquifer system ranged from 

33 to 85 percent (fig. 48B). There was a high fraction of river 

water in the groundwater at the Clear Springs IAS well (85 

percent) and LW1P IAS UA (74 percent), indicating a direct 

connection with the Peace River and the open interval of these 
76 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

These sections are located in the intermediate aquifer system 

and are composed of fractured dolomite at depths of 30 to 

60 ft and 90 to 100 ft below land surface. In addition to the 

fractured dolomite, large volumes of water have been observed 

to drain into Dover Sink, suggesting that a large cavernous 

conduit system exists. Based on measurements presented 

previously, the cavernous system associated with Dover Sink 

can store up to 10 Mgal/d under certain conditions. 

The existence of a highly transmissive, cavernous 

conduit system was documented during a dye test conducted 

by McQuivey and others (1981). A dye tracer injected into 

Dover Sink was detected in a water sample collected from an 

Upper Floridan aquifer well located about 1 mi south of the 

injection site. The peak concentration of the dye arrived within 

8 hours after injection, indicating a substantial hydraulic 

connection between Dover Sink and the Upper Floridan 

aquifer well. During this dye test, water moved at a rate of 

about 0.25 ft/s, which is similar to the velocity of a slow 

moving stream. Estimated velocities of regional groundwater 

flow in the Upper Floridan aquifer are substantially lower (2.0 

x 10-7 ft/s; Plummer, 1977).

20 31 10 20 30 10 19

2008

WATER LEVEL, IN FEET ABOVE NGVD 1929

LW3P IAS LA

LW3P UFA

LW4P UFA

LW4P IAS UA

90

85

80

75

70

65

60

55

50

90

85

80

75

70

65

60

55

50 O

2006 2007

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

r Gator Sink and = 0.93 2 LW3P IAS LA

r Gator Sink and LW3P UFA = 0.94 2

(C) (D)

GATOR SINK

CLEAR SPRINGS IAS LA

LW3P UFA

LW1P UFA

LW3P IAS LA

GATOR SINK

LW3P UFA

DOVER SINK,

dotted when dry

93

90

87

84

81

78

75

72

69

66

95

90

85

80

75

70

65

60

55 O

2006 2007

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

(A) (B)

CLEAR SPRINGS

IAS LA

LW3P IAS LA GATOR SINK

2 10

March April May

CLEAR SPRINGS IAS LA

PEACE RIVER AT CLEAR SPRINGS,

dotted when ponded Intermittent

recharge events

DOVER SINK,

dry when flatlined

r and Clear Springs IAS LA = 0.94 2 Dover Sink

EXPLANATION

r

2 COEFFICIENT OF DETERMINATION BETWEEN

WATER LEVELS (all regressions significant to

alpha level of 0.05)

UFA

SA

IAS

UPPER FLORIDAN AQUIFER

SURFICIAL AQUIFER

INTERMEDIATE AQUIFER SYSTEM

UPPER ARCADIA AQUIFER

LOWER ARCADIA AQUIFER

UA

LA

October November

30

December

312520151051 10 155 20 25 10 155 20 25 31

2006

5 15 25 5 15 25 5 15

Figure 49. Comparison of water levels in wells and sinks within the upper Peace River karst area (location of wells and 

sinks are shown in fig. 13B and well depths and cased intervals are shown in table 5).
Summary and Conclusions 77

Part of the water captured by Dover Sink migrates to 

the LW3P well site located about 1,000 ft south of the sink. 

Hydrographs in figures 46B and 49B indicate that the recharge 

water from Dover Sink augments Upper Floridan aquifer 

water levels at the LW3P well site. The effects of recharge 

water can be observed when aquifer levels at the LW3P 

UFA well rise above those of the LW1P UFA well (fig. 46B). 

The LW1P well site is upgradient from the LW3P well site 

and, therefore, water levels are typically higher near the 

LW1P well site. When Dover Sink is dry, the water levels in 

the LW3P UFA well return to more typical gradient conditions where they are lower than those in the LW1P UFA well. 

Water-level fluctuations in the wells near Dover Sink demonstrate the rapid movement and extent of the recharge waters.

Hydrographs of Gator Sink, LW3P IAS LA, and LW3P 

UFA wells indicate a high degree of interconnection between 

the sink, the intermediate aquifer system, and the Upper 

Floridan aquifer (fig. 49C). For the May through July 2007 

period, figure 49C indicates that water levels at Gator Sink 

were higher and fluctuated more than those of the underlying aquifers, with water levels in the sink fluctuating as 

much as 6 ft on an approximate weekly basis. During these 

water-level fluctuations, groundwater was observed seeping 

into the northwestern side of the sink through cracks and 

fissures. These unusual fluctuations were found to be related 

to streamflow losses that occurred at the upstream Ledges 

Sink and Catacombs Complex, as well as recharge water 

from a sprayfield located 0.5 mi west of Gator Sink. Both 

of these recharge sources eventually drain into Gator Sink. 

During low-flow conditions, Gator Sink is a low point in the 

surrounding floodplain that preferentially recharges the groundwater system. 

Hydrographs from Gator Sink and a number of wells 

along the river illustrate a large pulse of water that was 

introduced into the groundwater system in response to a large 

rain event that occurred on April 1, 2008 during the dry season 

(fig. 49D). The elevation in the Peace River was high enough 

(greater than 88 ft above NGVD 1929) for river water to 

travel down Gator Sink Distributary and fill Gator Sink. The 

hydrographs in figure 49D show the large rise in the water 

levels of Gator Sink, with this water eventually draining into 

the underlying aquifers. Data from the nearby LW3P IAS 

LA well indicate that water levels in the lower Arcadia aquifer 

rose about 20 ft during this event (fig. 49D). The hydrographs 

also illustrate that, although the storage capacity of the 

underground cavities in the intermediate aquifer system was 

temporarily met, the water stored in these cavities continued 

to drain downward into the underlying Upper Floridan aquifer 

because of the large water-level difference between these two 

aquifers that created the potential for downward flow.

Summary and Conclusions

The upper Peace River from Bartow to Fort Meade, 

Florida, is described as a groundwater recharge area, reflecting 

a reversal from historical groundwater discharge patterns that 

existed prior to the 1950s. Historically, the area along the 

river contained artesian wells and a second magnitude spring 

(Kissengen Spring) that discharged an average of 20 Mgal/d 

(31 ft3/s) into the Peace River. However, groundwater levels 

began to decline as early as the 1930s with an increase in 

groundwater use for mining and agricultural purposes. Due to 

this increased water use, a 40-ft decline in groundwater levels 

over a 20-year period has resulted in the cessation of flow of 

the artesian wells and Kissengen Spring, and flow now moves 

downward from the surface into the underlying aquifers.

Over time, declines in streamflow have been influenced by 

a number of factors, and these losses have been attributed to the 

following: (1) rainfall deficits; (2) large groundwater withdrawals 

that have lowered the potentiometric surfaces of the intermediate 

aquifer system and Upper Floridan aquifer beneath the riverbed; 

(3) changes in the natural drainage patterns of contributing 

streams to the Peace River; (4) altered surface sediments that 

affect surface runoff, infiltration, and baseflow characteristics of 

the basin; and (5) numerous karst features found in the low-water 

channel and floodplain that have enhanced the loss of streamflow. 

A trend analysis of long-term streamflow data from the USGS 

Bartow gaging station shows a significant decline in streamflow 

during the 1940s, 1950s, and 1960s; during the 1970s, streamflow 

remained statistically unchanged. Another trend analysis 

conducted using 1970s to 2003 data indicates a continued decline 

in streamflow during this period.

The upper Peace River is located in a basin that has been 

substantially altered by phosphate mining. Phosphate-mined 

land makes up the largest land-use category in the upper Peace 

River basin. Previously mined areas contain a large amount 

of clay-waste byproduct, which typically occupies about 40 

to 60 percent of the postmined landscape. Because of the 

low hydraulic conductivity of clay, groundwater recharge 

and movement through a clay-settling area, or other altered 

landscape associated with mining, is substantially less than it 

was during predevelopment conditions. 

The amount of flow derived from contributing tributaries 

has declined in the upper Peace River, because much of the 

natural drainage system of these tributaries has been altered by 

phosphate mining or agricultural activities. One of the largest 

tributaries is the Peace Creek Drainage Canal, which has been 

greatly altered by mining, and urban and agricultural development. Other tributaries such as Saddle Creek, Six-Mile Creek, 

Cedar, Bear, Hamilton, and Barber Branches, and Phosphate 

Mine Outfall CS-8 have all been altered as a result of phosphate 

mining. The meandering reaches and sloping gradients were 

replaced by flat ditches and clay-settling ponds that could 

store large quantities of water. Therefore, a component of the 
78 Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Florida

inflow to the upper Peace River has been lost because of altered 

drainage patterns, impoundment of water into clay-settling 

areas, and losses from these ponds due to evaporation.

The groundwater and surface-water interactions along 

the upper Peace River have been substantially altered because 

of groundwater use. Groundwater use has created a long-term 

decline in the potentiometric surface of the Upper Floridan 

aquifer that has affected interactions between the Peace 

River and the underlying groundwater system. When the 

potentiometric-surface levels of the underlying aquifers are 

lower than the elevation of the Peace River channel bed and 

floodplain, the potential for downward flow or recharge is 

initiated, which causes streamflow declines. When groundwater 

use for mining processes was at its greatest during May 1975, 

the potentiometric surface of the Upper Floridan aquifer was 

as much as 50 ft below the elevation of the riverbed along the 

upper Peace River. 

As mining extraction processes have changed and mine 

operations have moved to areas south and west of the upper 

Peace River basin, groundwater use for mining has declined. 

The May 2007 potentiometric-surface map of the Upper 

Floridan aquifer indicates a rise in aquifer water levels from 

the 1975 levels, but levels remain as much as 30 ft below the 

Peace River floodplain elevation. Although groundwater levels 

have increased since the days of intense mining operations, 

the levels have not fully recovered, because there has been a 

redistribution of some of the pumping stresses due to population growth and agricultural expansion in the Southern WestCentral Florida Groundwater Basin.

The upper Peace River is in a region where the river and 

floodplain are characterized by extensive karst development 

with numerous fractures, crevasses, and sinks that have been 

eroded in the limestone bedrock. With the reversal in groundwater head gradients, river water drainage into the underlying 

groundwater system through these karst features constitutes 

much of the streamflow loss in this region. Seepage runs were 

conducted along a 13-mi segment of the Peace River, from 

Bartow to Fort Meade, to define where the greatest streamflow 

losses occurred. Based on these seepage runs, the greatest 

streamflow losses occurred along an approximate 2-mi section 

of the river, located about 1 mi south of the Peace River at 

Bartow gaging station. About 10 karst features were responsible for the greatest streamflow losses along these reaches. 

Losses from individual karst features ranged from 0.22 to 

16 ft3/s based on measurements made between 2002 and 2007.

 Along the upper part of this 2-mi section (in Reach 1), the 

largest and most consistent streamflow losses occurred at the 

Ledges Sink, with measured losses ranging from 1 to 8 ft3/s. 

Located at the end of this 2-mi section (in Reach 2) is Dover 

Sink, which was the most influential karst feature along the 

upper Peace River and had measured losses ranging from 2 to 

16 ft3/s. The largest measured streamflow loss for all the karst 

features in Reaches 1 and 2 was about 50 ft3/s (32 Mgal/d) on 

June 28, 2002. 

During this study (2002-2007 water years), streamflow 

was influenced by climatic conditions. The discharge in 

the river was greatest for the 2005 water year as a result of 

above-average rainfall that occurred over a 3-year period 

(2003-2005). Average annual discharge for the 2005 water 

year at the Peace River at Bartow gaging station was 545 ft3/s, 

more than double the long-term average of 227 ft3/s for the 68 

years of record. The discharge in the river was lowest during 

the 2007 water year when the cumulative rainfall deficit was 

almost 29 in. over a 2-year period. Average annual discharge 

for the 2007 water year was only 18 ft3/s, and was the lowest 

on record for Peace River at Bartow.

Streamflow losses were related to the decline in the 

potentiometric surfaces of the intermediate aquifer system and 

the Upper Floridan aquifer below the riverbed elevation during 

below-average conditions along the upper Peace River. When 

groundwater levels were at their lowest level at the end of the 

dry season (May and June), there was an increased potential 

for streamflow losses. During this study, the largest streamflow 

losses occurred at the beginning of the summer rainy season 

when discharge in the river increased and large volumes of 

water were needed to replenish large unfilled cavities and void 

spaces in the underlying aquifers. 

The response of the river to changing groundwater levels 

was different in Reach 1 than in Reach 2. In Reach 1, the 

intermediate aquifer system is hydraulically connected to the 

river, and streamflow losses during below-average conditions 

were proportional to water-level changes in this aquifer. During 

the dry season in Reach 1, there was an increased potential for 

streamflow losses as aquifer levels declined, and as aquifer 

levels increased during the rainy season, streamflow gains 

were noted in Reach 1. In Reach 2, the upper Peace River is 

connected to both the intermediate aquifer system and the 

Upper Floridan aquifer through a large conduit system that 

is associated with Dover Sink. Because this conduit system 

is very large, it can accommodate a large proportion of flow 

from the river at multiple river stages. 

The underlying geology along the upper Peace River and 

floodplain is highly karstified and aids in the movement and 

amount of streamflow that is lost to the groundwater system in 

this region. Numerous karst features and fractured carbonates 

and cavernous zones observed in geologic cores and geophysical logs indicate an active, well-connected, groundwater 

flow system. Aquifer and dye tests conducted along the upper 

Peace River indicate the presence of cavernous and highly 

transmissive layers within the floodplain area that can store 

and transport large volumes of water in underground cavities. 

A discharge measurement made during this study indicates 

that the cavernous system associated with Dover Sink can 

accept more than 10 Mgal/d (16 ft3/s) of streamflow before the 

localized aquifer storage volume is replenished and the level of 

the sink stabilizes. Dover Sink stabilized when the pool of the 

sink rose to the level of the Peace River, which was about 87 ft 

above NGVD 1929, and water levels of the interconnected 

aquifers were about 78 ft above NGVD 1929.
References Cited 79

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