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H

H

H

H

H

Ona

Tampa

Ocala

Venus

DeLand

Venice

Bartow

Ruskin

Brandon

Parrish

Palatka

Tavares

Orlando

Seville

Placida

Dunedin

Bronson

Gardner

Arcadia

Sebring

Sarasota

Lorraine

Bushnell

Oklawaha

Leesburg

Lakeland

Mulberry

Pineland

Suwannee

Palmdale

La Belle

Basinger

Wauchula

Englewood

Bradenton

Chiefland

Inverness

Homosassa

Kissimmee

Polk City

Davenport

Dade City

Avon Park

Fort Myers

Clearwater

Cross City

Fort McCoy

Rock Ridge

Plant City

Fort Ogden

Frostproof

Lake Wales

Fort Meade

Cape 

Coral

Punta Gorda

Myakka 

Head

Myakka City

Saint Cloud

Lake Alfred

Citrus Park

Zephyrhills

San Antonio

Brooksville

Port Richey

Gainesville

Lake Placid

Winter Haven

Daytona Beach

Fort Lonesome

Crystal River

Tarpon Springs

Port Charlotte

St. Petersburg

Altamonte Springs

STARKEY

DUNEDIN

CROSS BAR

RANCH

BELLEAIR

CYPRESS CREEK

MORRIS

BRIDGE

SOUTH CENTRAL

NW HILLSBOROUGH 

DISPERSED

EAST

LAKE

VERNA

ELDRIDGE

WILDE

NORTH

PASCO

ODESSA

COSME

SOUTH PASCO

LAKELAND

SECTION 21

PINE ISLAND SOUND

CHAR LO TTE

HA

RB

O

R

CALOOSAHATCHEE

RIVER

LAKE

OKEECHOBEE

Shell Creek

Prairie

Creek

Horse Creek

Peace River

Big Slough Canal

Deer Prairie

Creek

Myakka River

LAKE

ISTOKPOGA

Lake

Jackson

Lake

Placid

Lake June

in Winter

Braden River

Manatee

River

Little Manatee River

S. Prong

Reedy

Lake

Lake

Livingston

Lake

Clinch

Crooked

Lake

Buffum

Lake

Peace River

Lake

Arbuckle

Lake

Wechyokapka

Lake

Rosalie

Tiger

Lake

LAKE KISSIMMEE

Lake Marian

TAMPA

BAY

HILLSBOROUGH

BAY

OLD TAMPA

BAY

Alafia River

N. Prong

Lake

Hancock

Lake

Garfield

Lake

Pierce

Lake

Jackson

Cypress

Lake

Lake

Gentry

Alligator

Lake

Lake

Preston

East Lake

Tohopekaliga

Lake

Hart

Lake Tohopekaliga

Lake

Conway

Lake

Hamilton

Lake

Marion

Lake

Juliana

Lake

Mattie

Lake

Parker

Lake

Thonoiosassa

Blackwater

Creek

River

Hillsborough

Withlacoochee

River

Lake

Tarpon

An c l o te

River

Pithlachascoiee

River

Crews

Lake

Lake

Monroe

Lake

Jessup

Lake

Harney

LAKE

APOPKA

LAKE

HARRIS

Lake

Dora

Lake

Griffin

Lake

Eustis

Lake

Dorr

Lake

Norris

Lake

Weir

Lake

Panasoffkee

Wekiva

River

Lake

Louisa

Lake

Minnehaha

TSALA

APOPKA

LAKE

Crystal River

Springs Group

LAKE

GEORGE

Lake

Woodruff

Lake

Disston

Lake

Kerr

ST. JOHNS RIVER

Oklawaha River

Orange

Lake

Lake

Stafford

CRESCENT

LAKE

Lochloosa

Lake

Newmans

Lake

ST.

JOHNS RIVER

Wekiva

River

River

Waccasassa

G U L F

O F

M

E X

I

C

O

ATLANTIC OCEAN

Lithia

Springs

Sulphur

Springs

Rainbow

Springs

Homosassa

Springs

WeekiWachee

Springs

Warm

Mineral

Springs

Chassahowitzka

Springs

Crystal

Springs

Crystal River Springs

L E E

P O L K

L A K E

D I X I E

TAYLOR

H E N D R Y

G L A D E S

O R A N G E

C I T R U S

M A R I O N

P U T N A M

D E S O T O

O S C E O L A

V O L U S I A

F L A G L E R

A L A C H U A

S A R A S O T A

S E M I N O L E

S T J O H N S

C H A R L O T T E

H I G H L A N D S

G I L C H R I S T

O K E E C H O B E E

P A S C O

H A R D E E

S U M T E R

M A N A T E E

P I N E L L A S

H E R N A N D O

H I L L S B O R O U G H

L E V Y

30

20

40

60

50

70

10

80

0

90

100

110

120

80

40

50

10

20

40

50

70

10

10

50

50

40

30

20

60

70

80

90

100

40

70

60

10

10

110

30

8

5

0

7

1

4

5

6

5

8

1

3 3

2 2

9

2 2

2 9

7

4

6

6

1

9

2 3

4 2

3 4 4

7

6 7

8

5

5

6

7

5 5

8

0 2 8

8

9 5

9

7

0

2

6

9

9

6

3

5

8

1

2

2

7 6

1

1 3

4

1

49

49

42

42

43

45

46

45

69

41

13

69

17

46

13

50

44

66

42

25

55

43

38

45

42

45

45

-8

57

74

66

65 71

58 60

50

28

25

32

27 25

27

10

22

51

40 45

40

46

10

36 41

22

34

33

51

33

27

30

69 34

36 49 44

50

10

41

38

14 36

31

44 48

36 46 45

26 39

17

62

39

11

13 48 38

39

32

41

38

52

15

57 76

75

58 77

76

75

38 42 19

61 80 34 38

40

50

71

84

65

49 9388 53 96

66

63

68

68 72

88

30 76

57 71

56

37 88

44 64

43 29 60 35 71 77

39

57

48

60

45

19

27

21

42 48

19

12

38

90

26 51 53 41 85

40 29 28

25

20 24 24

17 90

20 45 94 92

37 16 38 89 86

14 19

78

81 21 23

79 73 16 17

88 14

14 65

15 44

11

10 55

92 12 31 94 98

97

11

21 46 62

15

10 14 42

12

92

84

61

77

61

76 78 21 76 10

11

60 61

28

10

11

23 79

14

43 56

18 73

43 11

-7 55

77

12

-4

35 30

13

15

39 13

33 14 18

36

32

37

65

42

42

45 18

34

16

41

43

41

13

21

20 17

25

22

22

26

88

34

49

84

79

94

69

63 76

63

11

10

32 13

13

36 12 15 25

38 24

41 56

58

31

55 58 24 67 52 68 70

70

86

115

118

109

102

108

108

101

122

125

124

100

124 125

126

110

6

7

8

1

5

6

6

16 67

44

29

16

10

13 24

-3

-4

57 58

81°

81°

82°

82°

83°

83°

84°

84°

29°

29°

28°

28°

27°

27°

SCALE 1:500,000

MILES

KILOMETERS

5 0 5 10 15 20

5 0 5 10 15 20

A

T LA

NT IC OCEAN

G U L F O F M E X I C O

STUDY AREA

MAP AREA

ALABAMA GEORGIA

FLORIDA

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

Prepared in cooperation with the

SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT

Scientific Investigations Map 3183

A.G. Ortiz , 2011, Potentiometric surface of the upper

Floridan aquifer, west-central Florida, May 2011

POTENTIOMETRIC SURFACE OF THE UPPER FLORIDAN AQUIFER,

WEST-CENTRAL FLORIDA, MAY 2011

By A.G. Ortiz

Base from Southwest Florida Water Management District digital data, 1992,

State Plane Florida East projection, NAD83

Copies of this map can be purchased from:

U.S. Geological Survey

Branch of Information Services

Box 25286

Denver, Colorodo 80225-0286

Figure 1. Change in potentiometric surface of the Upper Floridan aquifer from May 2010 to 

May 2011 in west-central Florida. Positive values indicate an increase in water-level altitudes.

Negative values indicate a decrease in water-level altitudes.

EXPLANATION

MUNICIPAL WELL FIELD

POTENTIOMETRIC CONTOUR -- Shows altitude at which water would have stood in tightly cased wells. Contour interval is 10 feet.

 National Geodetic Vertical Datum (NGVD) of 1929. Hachures indicate depressions. Dashed where approximately located.

BOUNDARY OF SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT

OBSERVATION WELL -- Number is altitude of water level in feet above or below NGVD of 1929.

SPRING

" CITY OR TOWN

OBSERVATION WELL -- Number is altitude of water level in feet above or below NGVD of 1929.

 Bold number indicates water levels corrected for salinity.

VERNA

A

20

16

20

EXPLANATION

Change in the potentiometric 

surface, in feet

(Positive values indicate an 

increase in water-level altitudes)

-5 to -9.99

>0 to 4.99

0 to -4.99

<= -10.00

HYDROLOGIC CONDITIONS IN WEST-CENTRAL FLORIDA

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the

middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central

Florida generally contain highly mineralized water. The water-bearing units containing fresh

water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the

principal source of water in the Southwest Florida Water Management District and is used for

major public supply, domestic use, irrigation, and brackish water desalination in coastal

communities (Southwest Florida Water Management District, 2000).

This map report shows the potentiometric surface of the Upper Floridan aquifer measured in

May 2011. The potentiometric surface is an imaginary surface connecting points of equal

altitude to which water will rise in tightly-cased wells that tap a confined aquifer system

(Lohman, 1979). This map represents water-level conditions near the end of the dry season,

when groundwater levels usually are at an annual low and withdrawals for agricultural use

typically are high. The cumulative average rainfall of 45.74 inches for west-central Florida (from

June 2010 through May 2011) was 6.85 inches below the historical cumulative average of 52.59

inches (Southwest Florida Water Management District, 2011). Historical cumulative averages

are calculated from regional rainfall summary reports (1915 to most recent complete calendar

year) and are updated monthly by the Southwest Florida Water Management District.

This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida

Water Management District, is part of a semi-annual series of Upper Floridan aquifer

potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have

been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May

and September from 1975 through 2010. Water-level data are collected in May and September

each year to show the approximate annual low and high water-level conditions, respectively.

Most of the water-level data for this map were collected by the U.S. Geological Survey during

the period May 23-27, 2011. Supplemental water-level data were collected by other agencies

and companies. Most water-level measurements were made during a 5-day period; therefore,

measurements do not represent a "snapshot" of conditions at a specific time, nor do they

necessarily coincide with the seasonal low water-level condition.

WATER-LEVEL CHANGES

Water levels in about 95 percent of the wells measured in May 2011 were lower than the May

2010 water levels (Ortiz, 2010). Data from 399 wells indicate the May 2011 water levels ranged

from about 12 feet below to about 2.5 feet above the May 2010 water levels (fig. 1). The largest

water level increase occurred in northeast Pinellas County. The largest water level declines

occurred in east-central Hillsborough County and south-central Polk County (fig. 1).

Water levels in about 99 percent of the wells measured in May 2011 were lower than the

September 2010 water levels (Ortiz, 2011). Data from 400 wells indicate the May 2011 water

levels ranged from about 25 feet below to about 0.5 feet above the September 2010 water levels.

The largest water level decline was in west-central Pasco County and the largest rise in water

levels was in east-central Manatee County.

ACKNOWLEDGMENTS

The author thanks Tampa Bay Water and CF Industries for their assistance with the collection

of data used to prepare this report.

SELECTED REFERENCES

Lohman, S. W., 1979, Ground-water hydraulics: U. S. Geological Survey Professional Paper 708,

72 p.

Ortiz, A.G., 2010, Potentiometric surface of the Upper Floridan aquifer, west-central Florida, May

2010: U.S. Geological Survey Scientific Investigations Map 3139, 1 sheet.

Ortiz, A.G., 2011, Potentiometric surface of the Upper Floridan aquifer, west-central Florida,

September 2010: U.S. Geological Survey Scientific Investigations Map 3148, 1 sheet.

Southwest Florida Water Management District, 2000, Aquifer characteristics within the

Southwest Florida Water Management District: Brooksville, FL, 123 p.

Southwest Florida Water Management District, 2011, Hydrologic conditions for the month of

May 2011: Brooksville, FL, 84 p.