4

4

4

4

4

4

4

4

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

""

"

"

""

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

"

P

PP

PP

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 AlfredCitrus 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

30

40

20

30

70

10

60

50

80

90

100

110

120

10

20 40

50

60

0

50

50

50

100

40

70

60

30

2010

40

40

40

50

40

10

10

70

50

10

90

50

7080

90

80

60

3020

10-10

30

5

8

9 09

8

22

2

5

9

3

3

5

5

8

4

1

45

5

7

1

33

121

1

1

65

9

8

6

2

2134

0

24

7

23

42

3 2 56

67

7

7

47

5 4

759

45

7

20

67

66

68 88

7

538

78

9

7

7

9

5

93

2

37

6

80

4

8

32

52

1954465219

49

45

5245

51 49

48 244844

4314

43

1449

42

46 4642423722

153936

4243 32

3452

34

37 16394627

3170

163542

464350 4413

511141

3740

1043

451735 49

38 1831

133244

49 2543

4753

5335

454737332415

6033

3742

1443

48

35 6336

28 39 6236

5313

1949

52 55 73 78

725679

29

737635

17

775931707935

3733 83

7040

4152 31

9641

794787 3466

5777 3168 60

46 908440

50 93

3873

932980

50585873 3132 3298

366160

6840

83

38 39

7236 33

4987

39 4156

96

44

39

55

5246

68

64

39

5354 44

78

40

80 4258

39

41

68

41

4244

44

40

4243

4444

44

3848

50

43

-2

37

44

40

44

42

-9

52

70

6162

6065

56

45

24

1928

21

11

22

10

19

3111

12

3610 1324

4023

392054

26

5355

63

2249 636467

79715128 63

4969

5187

29

68393823 58

25 68 72

3352

44 56

4015

2014

3837 41

15

10

368721

504834

8238

2324

2117

2221

20

15 8891

1742

8933

15 8787

8413 1576 7921

177714 53

6914 15

8513 15

10 57

6113

13 3510

489510

23 94105610

56

57

38

3493

821555

-4 7755-2

7375

7413

-7

53 54

18

107913

1249

36

42

36 50

76

-4 292311

12

-7

3112 35

36

35

64

39

40 441530 4042

11

161715

39

20

22

4421

25

86

22

64

3228

63

48

79

73

90

67

53

43

11

106 113105

120123

122

122123 124

114

116106

110

100

100

-15

-18

-17-16

-15

STARKEY

DUNEDIN

CROSS BARRANCH

BELLEAIR

CYPRESS CREEK

MORRISBRIDGE

SOUTH CENTRAL

NW HILLSBOROUGH DISPERSED

EASTLAKE

VERNA

ELDRIDGEWILDE

NORTHPASCO

ODESSACOSME

SOUTH PASCO

LAKELAND

SECTION 21

PIN

E ISLA

ND

SO

UN

D

CHAR LO TTE

H

AR

BO

R

CALOOSAHATCHEERIVER

LAKEOKEECHOBEE

Shell

Creek

Prairie

Creek

Hor

se C

reek

Peac

e Ri

ver

Big

Slo

ugh

Cana

l

Dee

r P

rair

ie

Creek

Myakka River

LAKEISTOKPOGA

LakeJackson

LakePlacid

Lake Junein Winter

Braden River

Manatee

River

Little Manatee River

S. Prong

ReedyLake

LakeLivingston

LakeClinch

CrookedLake

BuffumLake

Peace R

i ver

LakeArbuckle

LakeWechyokapka

LakeRosalie

TigerLake

LAKE KISSIMM

EE

Lake Marian

TAMPA

BAY

HILLSB

ORO

UG

H

BAY

OLD TAMPABAY

Alafia

RiverN. P

rong

LakeHancock

LakeGarfield

LakePierce

LakeJackson

CypressLake

LakeGentry

AlligatorLake

LakePreston

East LakeTohopekaliga

LakeHart

Lake Tohopekaliga

LakeConway

LakeHamilton

LakeMarion

LakeJuliana

LakeMattie

LakeParker

LakeThonoiosassa

Blackwater

Creek

Rive

r

Hillsborough

Withlacooch

ee

River

LakeTarpon

An c l ote

River

Pithlachascoiee

River

CrewsLake

LakeMonroe

LakeJessup

LakeHarney

LAKEAPOPKA

LAKEHARRIS

LakeDora

LakeGriffin

LakeEustis

LakeDorr

LakeNorris

LakeWeir

LakePanasoffkee

Wek

iva

River

LakeLouisa

LakeMinnehaha

TSALA

APOPKA

LAKE

Crystal RiverSprings Group

LAKEGEORGE

LakeWoodruff

LakeDisston

LakeKerr

ST. JOHNS RIVER

Oklaw

aha

River

OrangeLake

LakeStafford

CRESCENTLAKE

LochloosaLake

NewmansLake

ST.

JOHNS RIVER

Wekiva

River

Riv

er

Wa

ccas

assa

GU

LF

OF

M

EX

IC

O

ATLAN

TIC O

CEA

N

LithiaSprings

SulphurSprings

RainbowSprings

HomosassaSprings

WeekiWacheeSprings

WarmMineralSprings

ChassahowitzkaSprings

CrystalSprings

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

81°

81°

82°

82°

83°

83°

84°

84°

29°

29°

28°

28°

27°

27°

SCALE 1:500,000MILES

KILOMETERS

5 0 5 10 15 20

5 0 5 10 15 20

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 2007. 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 41.21 inches for west-central Florida (from June 2006 through May 2007) was 11.63 inches below the historical cumulative average of 52.84 inches (Southwest Florida Water Management District, 2007). 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 the period May 21-25, 2007. 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 and Dixon, 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 low water-level condition.

WATER-LEVEL CHANGES

Water levels in about 71 percent of the wells measured in May 2007 were lower than the May 2006 water levels (Ortiz, 2007). Data from 399 wells indicate the May 2007 water levels ranged from about 21 feet below to about 8 feet above the May 2006 water levels (fig. 1). Significant water level declines occurred in north-central Pasco County and south-central Hernando County. The largest water level rises occurred in the southern half of Hardee County (fig. 1). Water levels in about 98 percent of the wells measured in May 2007 were lower than the September 2006 water levels (Ortiz, 2007). Data from 404 wells indicate the May 2007 water levels ranged from about 42 feet below to 7 feet above the September 2006 water levels. The largest water level decline was in north-central Manatee County and the largest rise in water levels was in south-central Sarasota 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. and Dixon, J.F., 2007, Potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity, Florida, May 2007: U.S. Geological Survey Open-File Report 2007-1371, 1 sheet.

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

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.

Ortiz, A.G., 2007, Potentiometric surface of the Upper Floridan aquifer, west-central Florida, September 2006: U.S. Geological Survey Open-File Report 2007-1228, 1 sheet.

Southwest Florida Water Management District, 2000, Aquifer characteristics within the Southwest Florida Water Management District: Broooksville, Fla., 123 p.

Southwest Florida Water Management District, 2007, Hydrologic conditions for the month of May 2007: Broooksville, Fla., 81 p.

Figure 1. Change in potentiometric surface of the Upper Floridan aquifer from May 2006 to May 2007 in west-central Florida. Positive values indicate an increase in water-level altitudes.Negative values indicate a decrease in water-level altitudes

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

-5 to -9.99

-10 to -14.99

-15 to -19.99

<-20.00

AT

LA

NT

IC O

CEA

N

G U L F OF M

EX

I CO

STUDY AREA

MAP AREA

ALABAMA GEORGIA

FLORIDA

U.S. DEPARTMENT OF THE INTERIORU.S. GEOLOGICAL SURVEY

Prepared in cooperation with theSOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT Open-File Report 2007-1380

POTENTIOMETRIC SURFACE OF THE UPPER FLORIDAN AQUIFER,WEST-CENTRAL FLORIDA, MAY 2007

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 SurveyBranch of Information ServicesBox 25286Denver, Colorodo 80225-0286

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. Italic number indicates water levels corrected for salinity.

NOTE: The potentiometric contours are generalized to synoptically portray the head in a dynamic hydrologic system, taking due account of thevariations in hydrogeologic conditions, such as differing depths of wells, nonsimultaneous measurements of water levels, variable effects ofpumping, and changing climatic influence. The potentiometric contours may not conform exactly with the individual measurements of water level.

VERNA

4

20

16

28