'
I

STATE OF GEORGIA DEPARTMENT OF NATURAL RESOURCES
Joe D. Tanner, Commissioner

THE GEOLOGIC AND WATER RESOURCES DIVISION Sam M. Pickering, State Geologist and Division Director

'

ATlANTA

1976

.

THE GEOHYDROLOGY OF BEN HILL, IRWIN, TIFT, TURNER, AND WORTH COUNTIES, GEORGIA

by

THOMAS W. WATSON

.

HYDROLOGIC ATLAS

GEORGIA DEPARTMENT OF NATURAL RESOURCES THE GEOLOG IC AND WATER RESOURCES DIVISION

THE GEOHYDROLOGY OF BEN HILL IRWIN. TIFT. TURNER. AND WORTH COUNTIES, GEORGIA
THOMAS W. WATSON

HYDROLOGIC ATLAS 2 SHEET 1 OF 3

A ~
I

Figure 1. THICKNESS OF THE NEOGENE FORMATION

B

- . ,.-:--. _,

160

90

140

'-'\.

83

'._...-.._fl

I

L---
320

/
I
)
; I

EXPLANATI ON

100 ______...,.. 150------

D

Denotes arc;~ where Neoge ne formations arc found ai or ncar the surface

Equal-thickness Contour Shows Uric/mess o( Neogene formation ouerfying the l'rindpal
Artesian Aqrli(er. Con lour intr~rua/ is 50 {t!ei

Control Point

Denol.cs area where Principal Artesian A(JUifer i~ found at or ne ar the .~urfacc

INTRODUCTION
Ben Hill, Irwin, Tift, Turner, and Worth Counties are located in southwest Georgia on the Coastal Plain. These five counties were selected for study because of their steady population growth in the past 10 years. New developments in agriculture, an abundance of good quality water, and an expanding transportation system promise to make this area of south Georgia one of continuing growth. Since ground water has been a significant aspect in the development of these counties, it is important to know how much water the aquifer is capable of producing, the quality of the water, and bow to insure the availability of this resource for continued use.
GEOLOGY
The surface sediment of the study area is primarily a sand-clay mixture that varies in thickness from less than 50 feet to several hundred feet. This series of shallow, unconsolidated sediments was deposited in the last 25 million years, a period of time known as the Neogene . Examinations of these sediments indicate that most were deposited in ancient seas that once covered the area. On the land surface, it is generally difficult to distinguish the contact between different geologic formations, since physical weathering and erosion commonly cause the contacts between adjacent rock units to appear gradational. In the southeastern portions of Tift and Irwin Counties, these Neogene age sediments become quite thick, as indicated by the contour lines on Fig. 1 and the type of sediment changes at depth from a mixture of poorly sorted sand and clay to very fine-grained, fissile clays and silts.
The principal artesian aquifer, which supplies water to all municipal and industnal wells and most deep domestic wells in this area, underlies the unconsolidated sediments: This aquifer consists primarily of the Suwannee and Ocala Limestone and many lens-shaped bodies of Neogene limestone overlying the Suwannee.
The principal artesian aquifer can be thought of as a wedge, roughly 250 feet thick in the northwestern portion of the study area, thickening to more than 400 feet in the southeast. If it were possible to remove the Neogene sands and clays, exposing the top of the principal artesian aquifer, one would see a rather rugged landscape. The surface of the principal artesian aquifer has been extensively eroded and marked with sinkholes, giving this buried surface considerable relief. When drilling, therefore, it is helpful to recognize that the depth to limestone can vary by tens of feet within a short lateral distance. Another important feature of interest to the well driller is found in southern Tift and Irwin Counties. Figures 1 and 3 both indicate a depression in the surface of the principal artesian aquifer along with a thickening of the overlying sediments. Within this depression the limestone is either missing entirely, or it exists at depths greatly exceeding those in other portions of the study area. High yield wells in this area are commonly difficult to complete because of the tight, impermeable clays fillin g the depression .
Most drilled wells in the study area draw at least part of their water from the principal artesian aquifer. Most domestic wells are drilled through t he sand and clay layers of the Neogene and are finished in the top few feet of the limestone. Water users who require more water than the average domestic well can provide, have drilled a larger diameter well or have drilled deeper into the aquifer. Pump and aquifer tests at the Tifton, Sycamore, and Fitzgerald city wells indicate that sustained yields of 1000 gallons per minute and more are possible for large wells tapping the principal artesian aquifer (Sever, 1969).

Scale I:250,000
E5========~O=======:::i'c:===:==:==:==:==:==:;:i'[:o=======::i"E===:==:==:==:c:===:=320 Statute Miles E53::::E3::::::E30====::::i'=::==::==::==::=3'10=====1E5c:=c:=c:==::=320====:::::i"~====330 Kilometers
SELECTED REFERENCES
1. Cooke, C. W., 1943, Geology of the Coastal Plain of Georgia: U. S. Geol. Survey Bull. 941 , 121 p. 2. Hem, J . D., 1970, Study and Interpretation of the Chemical Characteristics of Natural Water: U. S.
Geol. Survey Water-Supply Paper 1473 (2d ed.), 363 p. 3. Herrick , S. M., 1961 , Well Logs of the Coastal Plain of Georgia: Ga. C:eol. Survey Bull. 70 , 462 p. 4. Herrick, S.M., and Vorhis, R. C., 1963, Subsurface Geology of the Georgia Coastal Plain : Ga. Geol.
Survey In f. Circ. 25, 78 p. 5. Herrick, S. M., and Wait, R. L., 1956, Ground Water in the Coastal Plain of Georgia: Am. Water
Works Assoc. Jour., Southeastern Sec., v. 20 , no. 1, p. 73-86. 6. Krause, R. E. , and Gregg, D. 0., 1972, Water from the Principal Artesian Aquifer in Coastal Georgia:
Ga. Div. Earth & Water, Hydrologic Atlas 1. 7. Owen, Vaux, Jr., 1963, Geo logy and Groundwater Resources of Mitchell County , Georg ia: Ga.
Geol. Survey Inf. Circ. 24, 38 p. 8. Sever, C. W., Jr., 1965 , Ground Water Resources of Bainbridge, Georgia: Ga. GeoL Survey lnf. Circ.
32, 10 p. 9. _ _ 1966 , Reconnaisance of the Ground Water and Geology of Thomas County, Georgia : Ga.
Geol. Survey lnf. Circ. 34, 14 p. 10. _ _ 1969, Hydraulics of Aqu ife rs at Alapaha, Coolidge, Fitzgerald, Montezuma, and Thomasville,
Georgia: Ga. Geol. Survey lnf. Circ. 36, 16 p. 11. Stiff, H. A., Jr., 1951, The Interpretation of Chemical Water Analysis By Means of Patterns: Jour.
of Petroleum Technology , v. 3, no. 10, p. 15-17. 12. Stringfield, V. T., 1966, Artesian Water in Tertiary Limestone in the Southeastern States: U. S.
Geol. Survey Prof. Paper 517 , 226 p. 13. U. S. Dept. of Comm ., 1963-72, Climatological Data of Georgia: National Oceanic and Atmosp heric
Administration, Environmen ta l Data Service. 14. U. S. Public Health Service, 1962, Drinking Water Stand ards: Public Health Service, Pub. 956.

500
mean sea level
500

WORTH CO. TURNER CO.

B 500
mean sea level
500

I CRISP co. TURNER co. I I I

TURNER co. IRWIN co.
~
~ u
~ 0
0
"'

~ >
"'

~ 5

0



~

0
~
0
<1

~"'

PRINCIPAL ARTES IAN AQU IF ER

TURNER CO. TIFT CO. PRINCIPAL ARTES IAN AQU IFER

c
500

e ~
~
N
~


~o0000::-~>:
"'

-" o
0

~
~
u
~
E
"0'

~

..~,..X .:;
;
::;

~
u ~

c'

500

mean ua levelr~~~~~~@~PR~IN~CI~PA~L~AR~TE~SIA~N~AQ~UI~FER~~~~~~~~~~~~g~~~g~~tmean sea level

500

500

Figure 2. GEOLOGIC SECTIONS



o 0 .
o0 >-

A'

-""'

500
JOOO
8' 500
mean sea level
500 1000

GEORG I A D EPART MEN T OF NA T U RAL R ESOURC ES TH E GEOL OGIC AN D WAT ER RESOURCES DI V ISION

THE GEOHYDROLOGY OF BEN HILL. IRWIN. TIFT. TURNER. AND WORTH COUNTIES. GEORGIA
THOMA S W. WATSON

HYDROLOGIC ATLAS 2 SH EET 2 OF 3

I
I
I
r-
" --- 172-- - -

Figu re 3. CONF IGU RATIO N O F T H E T OP O F TH E PRI NCI PA L A RT ESI A N AQUI FE R

' zoo --- -

.
164

\

188

r-- f

- 55
L_~

EXPL ANATIO N
~------100 _ _ _ _ . . . . . . . - - ---125------------
Structure Contour Map Co nn ect s p o in ts o n lop o( tlw Pr in cip al Artesia n A qu i f er, w/Jic/J are o{ equal e levation a bove m ean sen le vel. Co n to ur interval is 5 0 feet
in areas be lo w M.!a le vel and 25 fee t in meas above sea level.

Control Point

I
_]3145 '
I
,.

1 2 r-----------------------------------------------------------------~
I I f10 f-

8 1-

1\

7-
w >
0
.Q
0
6-

5 ~
v

_j
w
>
w
_j
1- 240
N_230

.... .. 2 _

.. .. .. LEVEL ... .

.. ... ...- 220

1-

v

II

- 210

1 1 1 1 1 oLJ,~ _o'~ILI L' ~J~~ l I LI L I ~ I _JjL"~ I ~I LI L I J~~l _LLLI ~I_JLj" ~ I I ~_LJ"~l 1~I LI L I I~Jj_" LLI L~ I L I J~Ll I~_I LI LI ~ Jo_I LLIL~_JL' l L I ILI~IL~ I 200

1968

1969

/970

197 1

1972

Figure 5. Chart comparing monthly fl uctuation in rainfall with water level fluctua t ion in a n observation well in Tifton, Georgia.

SCALE 1: 250,000
''E=r:=:E==r= ::E=30= ==== ==::::i':=:=::=o:=:=:=:=:=:=:=:===::=i0i ========15E:=:=:=:=:=:=:=:=:=:==:==:=320 Statute Miles
''Ecao=3====::::1=:==:==:==:=31 0====::i"=:==:==:==:=~'I::o====="E=:==:==:==330 Kilometers
Figure 4. WATE R L EV EL IN TH E PRINCIPAL A RT ESIAN A QU IF ER

RAINFALL
Rainfall in southwest Georgia averages approximately 46 inches per year. An examination of rainfall data, however, shows that rainfall is not evenly dist ributed throughout the year (U. S. Dept. of Comm., 196 2). Wet months ca n be followed by ex tremely dry months during which water sources at or near the surface are depleted by evaporation. A fract ion of the rainfall is not returned directly to the atmosphere but is absorbed by the earth and percolat es downward into the layers of rock and sediment. This water is stored underground in a natural water supply system that is the principal artesian aquifer. Since evaporation has only a small effect on ground water levels in the report area, deep wells generally maintain adequate water levels during periods of drought.
Figure 5 shows t he water level record of a U. S. Geological Survey observat ion well in Tift on, along wit h rainfall records for the same time period. It can be seen that the monthly rainfall variation is rather high, whereas the water level in the well fluctuat es much less .
WATER LEVEL
The water level map of the principal artesian aquifer is constructed from measurements of water levels in wells known to t ap this aquifer. Geologic conditions in the report area are such that the ground water is under pressure, causing it to rise in a cased well, above the level at which it is first encountered in drilling. The aquifer in the study area is thus an artesian aquifer. The water level map can be used to predict the unpumped water level in a proposed well by subtracting the elevation of the ground water level from the elevation of the land surface at the well site. The remainder will be the approximate distance from the land surface to the static water level in the complet ed well. It should be emphasized that this is strictly an estimate of static water level. Actual levels may vary some what. Generally, the contours are more reliable where data points are closely spaced.
To date, pumping has no t caused any obvious changes in water levels of the principal artesian aquifer in the study area. Heavy dependence upon ground water from deep wells is comparatively recent. This office, in cooperation with the U. S. Geological Survey will continue to monitor water levels and ground water quality in this area to detect any changes which might affect gr0:<Hd water availability.

I

'"""\ --------- - ------

.217
\

TURNER COUN TY

.298

261

22

\ 2:9

90

I

~- ~3J_l_ l . _ _2i<._

208

( IRW IN COUNTY

33

<::-'

' \

.251

I

l' /I~

268

,J
L,

l
I

.231

1 245

'--

266
f
'
. 228
233

.222

223

I
r __ j

I

5

1>--I
zl

219

223

8[;:)

~--

----..---132)...._/ /
~I

1- ,.J

24 5

::>

226 .01

u

I

~ ~ u 227

:3 1

225

']
50 r

.238
235

234

\
\ \
\

I I

I

L _--

~N_HILL gouN~

1 2 15

I -

II
./ -

J1 IRWIN
- - -

COUNTY

-

226 .

221 231

_j
1 '::H---------------- r 194 190
193
I ) / ' I
731 30'

COUNTY

1/

---------~_/

I
I
I
J
r"
'

"i '~-

EX PLANATION
1oo--------

125- - - - - - - -

L ____ _ _ _
84

18 9

188

WORTH CO

Water Level Co ntour or Potentiometric Surfaee map Sho ws alii tude of artesian water aboue rni' an sea lr:vcl. Co n /(mr interuul is 25 feet.

Control Poin t

GEORGIA D EPARTMENT OF NATURAL RESO U RCES TH E GEOLOGIC AND WATER RESOURC ES DIVISION

THE GEOHYDROLOGY OF BEN HILL, IRWIN, TIFT, TURNER, AND WORTH COUNTIES, GEORGIA
THOMAS W. WATSON

HYDROLOGIC ATLAS 2 SHEET 3 OF 3

32

39

23 36
33 30
21 22

26

24

35

48

I
3145' [
I
(
<::'" ' \ \ \ I l :::> .J L, I \ I L_ r-L-
I
3 130' ~
'--]
112

'....-- '

_ _ _ _ .J

~ I

I33 I

I

2.7

I

I

35

I

33

36

I

I- - -

112

'

'v-
\)

29,

~FT

COUNT Y

'v1 5

34
9
13

\

24

90

\

90

I

\ __5_o _ ,1-1-l 39
( 1 IRWIN COUNTY

46

26

I

Fitzgerald

45
I

I

47

r- _j

I
,_/
!zl
8!
.........- - i - - - - - - { 3 2
~~
0::
=>I
~

---,
38 32.

rB.EN=HI-LL-C-OU-NT-Y - -

43

, IRWIN COUNTY

j I I - _ _

r-'
' , ~
r_j
Ocilla

l_ 42

I
4 9 C---~

I
I 51

\

4

\ 16

II

\

I

)

I

42

I

I

j3 130'

II

\

I

ar - - - - - ...._____ , ___ J

IRWIN

COUNTY

~

------~

II_j3145' 47 t _ _ _ _ _ _ J _ _ __ ____.
I
I
J
43

I 15

7

I

I

.28

'_j

20

I

I

6

,.-J

rj

49

,__I

51

WORTH

. 22
CO-UN-TY- - - - ,

~-

I

__L ___ - -TI-FT-C-OU-NTY- - -2.

,_

r jI
- _r'

, - - - - - -- - - - , - - - - - - - - - - , L- - - '

8 3 30'

31
10

SCALE 1=250,000

'"-==r::=:E3:::=:JEolO=======:}'=:==_::=:==:==:==:==;=iJ:IO===:::====i"~=:==:==:==;;;=;~20 Statui~ Miles

t::

B==0 B==~~~ 10 ==15 ~~~ 20 ==~ 25 ~~30 Kilometers

Figure 6. Map showing Stiff Diagrams of selected wells in study area.
23 Identification number of well with Stiff Diagram
34 Id entification number of well

7 9

Concentration in Milliequivalents Per Liter

5

4

3

2.

0

2.

3

4

5

~I~ ;;11----------I-+----+---.-+1------lK<f-'-----+-=-t1f--+----+-----+-1---+-------11

Example of a Typical Stiff Diagram

GROUND WATER QUALITY
Chemical characteri~tics of ground water are the result of the water being in close, prolonged contact with the rocks and minerals that serve as the aquifer. All rocks and minerals are soluble to a certain extent. The length of time that the water is contained underground, combined with a complex of other factors, determines the chemical quality of the water when it is pumped to the surface .
Analysis of water samples taken in the study area shows the water to be fairly uniform in quality. In general, the samples are classified as a calcium bicarbonate type water, moderately hard, but low in total dissolved solids. All chemical constituents examined were within recommended limits for drinking water as set forth by the U. S. Public Health Service (1962), except for local instances of excessive iron. Although a high iron content is not harmful to humans, it does cause iron staining. Since irrigation is becoming an important factor in agriculture of the Coastal Plain , it is worthwhile to note that the chemical quality of ground water in the study area is suitable for irrigation.
The Stiff Diagrams (Stiff, 1951) displayed in Figure 6 are an effective method of showing differences or similarities in ground water composition. Each diagram represents the same dissolved solids from an individual water analysis. It is essentially a graph of major dissolved constituents. By com paring the graphs, differences or similarities in the water types are often apparent. Figure 6 shows the array of diagrams representing typical well waters in the area.