HIGHLANDS

DIXIE

G I L C H R I S T

LEVY

ALACHUA

PUTNAM

S T . J O H N S

MARION

FLAGLER

VOLUSIA

LAKE

S E M I N O L E

ORANGE

CITRUS

HERNANDO

SUMTER

PASCO

PINELLAS

HILLSBOROUGH

OSCEOLA

POLK

HARDEE OKEECHOBEE

D E S O T O

MANATEE

SARASOTA

CHARLOTTE

LEE

GLADES

HENDRY

VERNA

SOUTH

CENTRAL

MORRIS BRIDGE

NW HILLSBOROUGH

DISPERSED

CLEARWATER

DUNEDIN

EAST LAKE

ELDRIDGE

WILDE

ODESSA

COSME

SECTION

21

STARKEY

CYPRESS CREEK

CROSS

BAR

Old Tampa

Bay

Hillsborough Bay

Tampa Bay

Lake

Panasoffkee

Alligator

Lake

Lake

Preston

Lake

Gentry

Cypress

Lake

Lake

Marion

Lake

Hamilton

Lake

Minnehaha

Lake

Louisa

Lake

Juliana

Lake

Mattie

Lake

Parker

Lake

Butler Lake

Conway

Lake

Hart

Lake

Thonotasassa

Lake

Hancock

Lake

Garfield

Buffunt

Lake

Crooked

Lake

Lake

Weohyakapka

Lake

Rosalie

Tiger

Lake

Lake

Arbuckle

Reedy

Lake Lake

Clinch

Lake

Livingston

Lake

Marian

Lake Jackson

Lake

Jackson

Lake

June-In-Winter

Lake

Placid

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

Ona

Venus

Ruskin

Bartow

Wimauma

Gardner

Brandon

Parrish

Lorraine

Mulberry

Lakeland

Bushnell

Riverview

Dade City

Bradenton

Avon Park

Inverness

Plant

City

Fort Ogden

Frostproof

Fort Meade

Lake Wales

Rock

Ridge

Zephyrhills

San

Antonio

Citrus

Park

Myakka City

Myakka

Head

Pine Island

Lake

Alfred

Fort Lonesome

Homosassa

Springs

Chassahowitzka

Springs

Rainbow

Springs

Weeki Wachee

Springs

Crystal

Springs

Sulphur

Springs

Lithia

Springs

Warm

Mineral

Springs

Crystal River

Springs Group

Silver

Springs

Rock

Springs

Wekiva

Springs Starbuck

Springs

Orange

Lake

Lake

Disston

Lake

Monroe

Lake

Jessup

Lake Eustis

Lake

Griffin 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

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 westcentral Florida generally contain highly mineralized water. The water-bearing units

containing freshwater 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

September 2006. 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 wet

season, when ground-water levels usually are at an annual high and withdrawals for

agricultural use typically are low. The cumulative average rainfall of 46.06 inches for westcentral Florida (from October 2005 through September 2006) was 6.91 inches below the

historical cumulative average of 52.97 inches (Southwest Florida Water Management

District, 2006). 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 since 1975. 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

September 18-22, 2006. Supplemental water-level 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 Orlando, Florida (Kinnaman, 2007). 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 high waterlevel condition.

WATER-LEVEL CHANGES

Water levels in about 56 percent of the wells measured in September 2006 were lower than

the September 2005 water levels (Ortiz, 2006). Data from 401 wells indicate the September

2006 water levels ranged from about 15 feet below to 20 feet above the September 2005 water

levels (fig. 1). Significant water-level declines occurred in north-central Pasco County,

south-central Hernando County, northeast Hernando County, and east-central Sumter

County. The largest water-level rises occurred in southern Hillsborough County, northern

Sarasota County, and throughout Manatee County (fig. 1).

Water levels in about 73 percent of the wells measured in September 2006 were higher than

the May 2006 water levels (Ortiz, 2007). Data from 410 wells indicate the September 2006

water levels ranged from 14 feet below to about 41 feet above the May 2006 water levels. The

largest water level decline was in south-central Hernando County, and the largest rise in

water levels was in northeast 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

Kinnaman, S.L., 2007, Potentiometric surface of the Upper Floridan aquifer in the St. Johns

River Water Management District and vicinity, Florida, September 2006: U.S. Geological

Survey Open-File Report 2007-1215, 1 sheet.

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

708, 72 p.

Ortiz, A.G., 2006, Potentiometric surface of the Upper Floridan aquifer, west-central Florida,

September 2005: U.S. Geological Survey Open-File Report 2006-1128, 1 sheet.

Ortiz, A.G., 2007, Potentiometric surface of the Upper Floridan aquifer, west-central Florida,

May 2006: U.S. Geological Survey Open-File Report 2007-1032, 1 sheet.

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

Southwest Florida Water Management District: Broooksville, 123 p.

Southwest Florida Water Management District, 2006, Hydrologic conditions for the month of

September 2006: Broooksville, 81 p.

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

0 10 20 30 KILOMETERS

0 10 20 30 MILES

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

September 2006 in west-central Florida. Positive values indicate an increase in water-level altitudes.

Negative values indicate a decrease in water-level altitudes.

20 or greater

15 to 19.99

10 to 14.99

5 to 9.99

-10 or less

0 to 4.99

-4.99 to <0

-9.99 to -5

CHANGE IN THE

POTENTIOMETRIC SURFACE,

IN FEET

EXPLANATION

SOUTHWEST FLORIDA

WATER MANAGEMENT

DISTRICT BOUNDARY

(Positive values indicate an

increase in water-level altitudes)

Lake

Okeechobee

Gulf of Mexico

27°

28°

29°

84° 83° 81°

27°

28°

29°

84° 83°

82°

82° 81°

POTENTIOMETRIC SURFACE OF THE UPPER FLORIDAN AQUIFER,

WEST-CENTRAL FLORIDA, SEPTEMBER 2006

By

A.G. Ortiz

A.G. O , 2007, Potentiometric surface of the upper Floridan aquifer, west-central Florida, September 2006

OPEN-FILE REPORT 2007 1228 −

rtiz

Prepared in cooperation with the

SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

Base from U.S. Geological Survey digital data.

Universal Transverse Mercator projection,

datum NAD83, units meters, zone 17.

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 KILOMETERS 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 1929).

SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT BOUNDARY

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

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

Atlantic

Ocean

10

10

50

100

110

120

110

50

60

70

80

100

90

80 70

60

50

40

30

20

10

70

50

50

50

10

20

30

40

40

50

40

60

10

40

30

20

50

60

70

80

90

20

20

10

70

80

70

50

60

10

20

40

80

70

60

30

50 40

30

20

15

25

55

45

23

47 46 52

48 51

52

50

42 50

61

46

41

51

47

49

44

50

35

32 38

32 31

32 36

48

47

25

31

34 23

48

49

49

50

47

72

45

50

41 50 49 28 30

22

49

25 48

24

40

36 28

52

83

44

85

62 46

43

45

73

46

40 46

48

96

91

88

83

87

84

69

87

63

77

100

60

43

57 59 48

103

104 109

106

4

8

3

6

39

23

7 6

5

9

6 9

7 9

6 6

3

1

8 8 7

6

11

46 48

43

43

39

18 19

12

15 18 15 12

15 43 11

15

42 62 12

25 40

41

15

40

60 33

45 11 28 77

11 12

77 30 46 15

15 19

75 76

23 52

19 13

49

22 24

63 72

45

62 17 21

19 38 31

23 54 51

21

21 36

22

38

8

8 13

28

21 26

18

7

9

5

3

4

4

2

2 6

4 5

4

5

9

70 58

15

15

13

17

64

54 58

65

24

51

31 66

45

44 28 61

32 50

21 49

11

26

16 84

76

79

55 68

76

15

81

111

116

22

60

56 54

30 32

27

41

24 19

17

18

25

21

34

35

81

74

72

47 87

43

77

41 56 90

61 44 45 40

50

44

50

71

69

75

66 68

66

59

34

40

27

27

40

57

68 68 70

86

53

51

53 70

71

79

59

45

39 92

89

97

98

47 95

92 89 82

62

84

23

97

62

95

82

77

95

71

104

124 127

126

101 125

127

118 122

112

117

80 81 38 88

40

87

48

57

50 83

92 69

65

79 68 47

86 92

48 53

97

44

97 85

59 63 62 79

41 65 65

100

102 101

108

54

45

40

43

41

46 48

53

42

47

52

53

57

50

2

20

11

11

54

64

57 76

76

31 74 80 38

43

61

4 3

4

7

4

4

7

7

5

2

2 3 3

2

2

8

7

38 43

36

34 54

27 31 71 35

38 46

51

53 13

42

10 19 11 39

35 11

33

18 45

45

51 56

37 48 46

39

36 28

19

63

38 11 17 54 49

39 66 39

32 39 40 65

16 40 79

82

8

4

52

56

48

54 22

51 47

54

47

53 47

49

49

46

44

19

50 43

11

10

42

43 48

19

41

44

49

47

45

45

28 27

45

34

83 58

73

70

96

42

4

35

39

127

78

26

6 14

3

7 8

9

7

47