HIGHLANDS

DIXIE GILCHRIST

LEVY

ALACHUA PUTNAM ST. JOHNS

MARION

FLAGLER

VOLUSIA

LAKE

SEMINOLE

ORANGE

CITRUS

HERNANDO

SUMTER

PASCO

PINELLAS

HILLSBOROUGH

OSCEOLA

POLK

OKEECHOBEE

HARDEE

DE SOTO

MANATEE

SARASOTA

CHARLOTTE

LEE

GLADES

HENDRY

Orange

Lake

VERNA

SOUTH

CENTRAL

MORRIS BRIDGE

NW HILLSBOROUGH

DISPERSED

CLEARWATER

DUNEDIN

EAST LAKE

ELDRIDGE

WILDE

ODESSA

COSME

SECTION

21

STARKEY

CYPRESS CREEK

CROSS

BAR

Cross City

Chiefland

Gainesville

Daytona

Beach

DeLand

Fort

McCoy

Bronson

Ocala

Altamonte

Springs

Orlando

Oklawaha

Leesburg Tavares

Crystal

River

Homosassa

Brooksville

Port Richey

Tarpon Springs

Dunedin

Clearwater

St. Petersburg

Tampa

Sarasota

Polk City

Winter

Haven

Wauchula

Arcadia

Venice

Englewood

Port Charlotte

Punta Gorda

Cape Coral

Fort Myers

La Belle

Palmdale

Lake

Placid

Sebring

Kissimmee

Saint

Cloud

50

80

40

30

20

50

60

70

80

90

100

110

120

10

0

10

110

100

90

80

70

60

50

40

30

20

10

50

50

60

70

50

50

50

10

20

30

40

40

80

70

70

60

60

50

Homosassa

Springs

Chassahowitzka

Springs

Rainbow

Springs

Weeki Wachee

Springs

Crystal

Springs

Sulphur

Springs

Lithia

Springs

Warm Mineral

Springs

5

57

42

30

17

13

48

5

3

7

106

5

5

9

9

16

53

49

2

34

28

4

15 3

13 51

8

5

47.8

53

5 39

8

7

66

83

32

35

65

46

38

72

48

82

82

46

48

49

4

2

4

6

5

11

8

4

1

4

3

2 2

1

2

1 9 7

58

2

26

2

2

3

4 59

1

68

32

35

1 4

9 19 3

3

5 42

16

89 24

5 6

7

6

8

7

5

10

8

1

7

9

5

5

9 3

1

12

22

6

5

8 6

6

9 9

81

5

3

57

1 64

1

3

42 43

41

18

22

9

79

50

56

21

55 28

49

57

56 54

52 27 51 49

47

17 47

16 52 45

11 11

43

45 51

46

40 25

16

44 38 45

47

35

56

35

41

43 19 51

31

72

54

17 36 47

43

52 56.37 49

17 57

45

15

45

44

21 48

40 54 48

14 19 43 33 27

23 37

29

48

53 58

48 49

63 23

66

41

14 41 47 21

49 56

50 41 67

35 41 43

41

63

18 41 20 81 54 55

59

61 79

35 87

36 76

79

83

42 45

64 85

39

86 75 43 88

44 41

90 74 45 64 35 81

47 84 54

92 39

72

80 62 82 35

85 66

52 94 80

47

58

98 42 85

97

84 66

77

36

36 36 110 42 68

69 73

88 66

77 43 41 55 89

46

62

48 36

43

128

61

69

44

57

58

79

45

46

44

63

44

46

73

51 46 43

46 47

47

49

45 46

48

49 49

48

40

62

45

40

11

44

48

46

-4

63

77

68 70

67 72

59 61

53

27

34

24

27

22

13

12

40

15

50

13

20

36

36

76

50 26

66

32

63

60 70

52 72 72

73

88 76

30

58

71

58 73 43

41

28 60 29

71

77

57

48

59

45 85

21

26 45 41 13

38 91 25 54 52

86

42

46

28

28

25

19 28

24

24

18 94 96

19

45 36 95 92

38 15 17 80 86

20

82.44 15

58

82

17

18 97

14

18

77

14 17 13 63

99 14

12 38 72 75

57 10

18 27

19 26 54 96

91

34 74

15 83

15 73 79

34 80

11

70 72

38

12 80

11 87 33

16

68

27 76

55

81

25

14 48

43 16

12

47

27

19 41

23 12

42 42

67

44

44

37

45 45 21

24

19

24

46

27

29 34

51

44

42

25

21

50

100

101 115

108

102

124

127

126

101 126

129

120 121

115

102

102

66

90

32

17

58

94 113

11 51

36

38

5

Lake

Disston

Lake

Monroe

Lake

Jessup

Lake Eustis Lake

Griffon

Lake

Dora

Lake

Harris

Lake

Woodruff

Lake

Harney

Lake

Weir

Tsala Apopka

Lake

Lake

George

Crescent

Lake

Lake

Kerr

Lochloosa

Lake

Newnans

Lake

Lake

Stafford

O

ah

klaw

a

River

St. n

J ho

s

River

St. Johns River

Lake

Apopka

East

Lake

Tohopekaliga

Lake Tohopekaliga

Lake

Kissimmee

Lake

Istokpoga

Waccasassa

River

St. Johns

River

Caloosahatchee River

Kissimmee River

P

i

ea

R

ce

ver

Suwannee

River

Manatee River

Myakk

e

a

Riv

r

G U L F

O F

M E X I C O

ATLANTIC OCEAN

ALABAMA

GEORGIA

FLORIDA

M A P A R E A

STUDY

AREA

HYDROLOGIC CONDITIONS IN WEST-CENTRAL FLORIDA

The Floridan aquifer system is 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 a highly

productive aquifer and supplies more than 10 times the amount of water pumped from

either the surficial aquifer system or the intermediate aquifer system in most of the

study area (Duerr and others, 1988).

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

measured in May 2005. 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 ground-water levels usually are at an annual low

and withdrawals for agricultural use typically are high. The cumulative average rainfall

of 67.27 inches for west-central Florida (from June 2004 through May 2005) was 14.20

inches above the historical cumulative average of 53.07 inches (Southwest Florida

Water Management District, 2005). The above average precipitation is attributed to

the active hurricane season for Florida in 2004. Historical cumulative averages are

calculated from regional rainfall summary reports (1915 to the most recent completed

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. Potentiometricsurface maps have been prepared for January 1964, May 1969, May 1971, May 1973,

May 1974, and for each May and September since 1975. Water-level data are collected

in May and September each year to show the approximate annual low and high waterlevel 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, 2005. Supplemental waterlevel data were collected by other agencies and companies. A corresponding

potentiometric-surface map was prepared for areas east and north of the Southwest

Florida Water Management District boundary by the U.S. Geological Survey office in

Altamonte Springs, Florida (Kinnaman, 2006). 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 19 percent of the wells measured in May 2005 were lower than the May 2004

water levels (Blanchard and others, 2004). Data from 409 wells indicate that the May 2005 water

levels ranged from about 5 feet below to about 18 feet above the May 2004 water levels (fig. 1). The

largest water level-declines occurred in southwestern Hernando County, northeastern

Hillsborough County, and portions of Hillsborough, Sumter, and Sarasota Counties. The largest

water-level rises occurred in southeastern Hillsborough County, eastern Manatee County, and

western Hardee County (fig. 1).

Water levels in about 95 percent of the wells measured in May 2005 were lower than the September

2004 water levels (Blanchard and Seidenfeld, 2005). Data from 405 wells indicate the May 2005 water

levels ranged from about 22 feet below to 14 feet above the September 2004 water levels. The largest

water level decline was in east-central Manatee County and the largest water-level rise was in

central Sarasota County.

ACKNOWLEDGMENTS

The authors thank the Southwest Florida Water Management District, Tampa Bay Water, and CF

Industries for their assistance with the collection of data used to prepare this report.

SELECTED REFERENCES

Blanchard, R.A., Seidenfeld, A.V., and McCulloch, D.S., 2004, Potentiometric surface of the Upper

Floridan aquifer, west-central Florida, May 2004: U.S. Geological Survey Open-File Report 2004-1399,

1 sheet.

Blanchard, R.A., Seidenfeld, A.V., 2005, Potentiometric surface of the Upper Floridan aquifer, westcentral Florida, September 2004: U.S. Geological Survey Open-File Report 2005-1222, 1 sheet.

Duerr, A.D., Hunn, J.D., Lewelling, B.R., and Trommer, J.T., 1988, Geohydrology and 1985 water

withdrawals of the aquifer systems in southwest Florida, with emphasis on the intermediate aquifer

system: U.S. Geological Survey Water-Resources Investigations Report 87-4259, 115 p.

Kinnaman, S.L., 2006, Potentiometric surface of the Upper Floridan aquifer in the St. Johns River

Water Management District and vicinity, Florida, May 2005: U.S. Geological Survey Open-File Report

2006-1006, 1 sheet.

Lohman, S. W., 1979, Ground-water hydraulics: U. S. Geological Survey Professional Paper 708, 72 p.

Southwest Florida Water Management District, 2005, Hydrologic conditions for the month of May

2005: Brooksville, Fla, 79 p.

≥ 10

5 to 9.99

0 to 4.99

< 0 to –4.99

CHANGE IN THE

POTENTIOMETRIC SURFACE,

IN FEET

EXPLANATION

0 10 20 30 KILOMETERS

0 10 20 30 MILES

SOUTHWEST FLORIDA

WATER MANAGEMENT

]DISTRICT BOUNDARY

(Positive values indicate an

increase in water-level altitudes)

Figure 1. Change in potentiometric surface of the Upper Floridan aquifer from May 2004 to May 2005

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

indicate a decrease in water-level altitudes.

Lake

Okeechobee

Gulf of Mexico

Atlantic Ocean

27°

28°

29°

84° 83° 81°

27°

28°

29°

84° 83°

82°

82° 81°

POTENTIOMETRIC SURFACE OF THE UPPER FLORIDAN AQUIFER,

WEST-CENTRAL FLORIDA, MAY 2005

By

A.G. Ortiz and R.A. Blanchard

A.G. O , 2006, Potentiometric surface of the upper Floridan aquifer, west-central Florida, May 2005

OPEN-FILE REPORT 2006 1009 −

rtiz and R.A. Blanchard

Prepared in cooperation with the

SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

Base from Southwest Florida Water Management District digital data, 1992

Universal Transverse Mercator projection, Zone 17, Datum NAD27

Copies of this map can be purchased from:

U.S. Geological Survey

Branch of Information Services

Box 25286

Denver, Colorado 80225-0286

5 20 MILES 0

5 20 MILES 0

POTENTIOMETRIC CONTOUR Shows altitude at which water would have stood in tightly cased

wells. Contour interval is 10 feet. National Geodetic Vertical Datum of 1929 (NGVD of 1929).

Hachures indicate depressions. Dashed where approximately located.

SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT BOUNDARY

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

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

Bold italic number indicates water level corrected for salinity.

MUNICIPAL WELL FIELD

SPRING

CITY OR TOWN

−

−

−

20

EXPLANATION

45

VERNA

Port Charlotte

29

NOTE: The potentiometric contours are generalized to synoptically portray the head in a dynamic hydrologic system,

taking due account of the variations in hydrogeologic conditions, such as differing depths of wells, nonsimultaneous

measurements of water levels, variable effects of pumping, and changing climatic influence. The potentiometric

contours may not conform exactly with the individual measurements of water level.