Potentiometric surface of the Upper Floridan Aquifer in Georgia, May 1985, and water-level trends, 1980-85

POTENTIOMETRIC SURFACE OF THE UPPER FLORIDAN AQUIFER IN GEORGIA, 1985
AND WATER-LEVEL TRENDS, 1980-85
by
John S. Clarke
Prepared in cooperation with the Department of the Interior, U.S. Geological Survey
Department of Natural Resources J. Leonard Ledbetter, Commissioner Environmental Protection Division Harold F. Reheis, Assistant Director
Georgia Geologic Survey William H. Mclemore, State Geologist
ATLANTA 1987
HYDROLOGIC ATLAS 16

GEORGIA DEPARTMENT OF NAT URAL RESOURCES ENVIRONMENTAL PR OTECTION DIVI S ION GEORGIA GEOLOGIC SURVEY

Prepa red 1n co op erat ion w1th the
UNITED STATE S DEPARTMENT OF THE IN TE RIO R GEOLOGIC AL SURVEY

HYDROLOGIC ATLAS 16

INTRODUCTION
The Floridan aqu1fer sys tem (forme rl y the pr1ne1pal .:~rtes1an aqu1fcr) 1S the mcnn source of groun~ ~o~ater 1n the Coastal P a1n of Georg1a. Abo ut 600 r1g al'd 15 withd r a ..m fro:n the upper part of the aqu1fer system (Upper Flor1dan aqu1fer) 1n Georgla, mostly for 1ndu stnal use and for 1rr1gatwn, 1\s a result of th1 s pum;:nng, large cones o f
depress1on 1n tre potent 1ometr1c surface have r crmed at Savannah, Brunsw1ck., Je~up, <lnd Sl !1arys, Ga.-Fernandlnil
Beach , Fla. Decl1n1ng water levels 1n these an d other
areas have caused concern 01er protect1on of the grounj-
~~ater resource. To mon 1to r water-level fluctuat1ons and tre nd s 1n the Flondan and 1n other aqu1fer~. the U. S. Geulog1cal Survey , 10 cooperat1on w1th the Georg1a Departmen': of /l atural Resource~. Env1ronmental Protect1on DiviSion, Geologic Survey Branch , and other State e~nd local a9enc 1es , operates a networ k of approx1mately 1,700 waterlevel monlton ng wells . 1nc lu d1 ng 149 equ1pped w1t~ cont1nuous water-le>el recorders.
Th1s. report tlep 1cts and descnbes the potent1ornetnc s ur face of t he Uppe r Flondan a qu1 fer 1 n Seorg 1a for /l ay 1985 . The potent1ometnc surface, wh ch rep rese nts lhe alt 1tude at wh1ch water ~auld have ~toad 1n t 1ght l y cased wells that tap the aqu1fer, was constructed f rom water - level a nd press ure measurements made 1 n more than 1,000 dells 1n Georg1a and adjacent parts of Al abama, South Caro l 1na , and Flonda du r 111q ~lay 13- 24, 1985. The report also dlScusses water - leve l f lo.~ctu at 1 o ns and trends 1n the Upper Flondan aqu1fer 111 d1ffere1l pctrts of t he Sta t e for 1980-85. The work was done 1n coopera t 1on w1th the Georg1a Department o f Natural Resources , Environmental Protect f on Di t1sfon, Ceolog1c Surv ey 13r[lnch, Chuthum County , Gl_vnn 2ounty, the c1t1es of Brunsw1ck and Valdosta, and the Albany Water, Gas , a nd L1ght Comm l SSlOn.
~1 aps shmnn g the po:ent10JTetnc su rface of the Upper Flor1 dan aqu1fer 1n Geo r 91a have been pr epared for earl1er penods 1u d1f f e r e11t parts of the Coa5ta1 Plcnn . Joi111S t on and others (1921) presen t ed a map show1ng the pot en t1om etr 1c surface of the Flondan aqu1fer system for the southeastern States 1 n Hay 1980 . The map was based on water-level [ln d pressur~ measurem~nts mule dunng t~ay 12-23 , 1980. fJ map show1ng the est 1TT1 ated potent10metn c su r face o f the dtJ ulfer 1r 1ts aree of occurrence pr1or t o development (about 1880) was compiled by Johnston and o t hers [ 1980). Krause and Randolph 11987\ present a map shovnng the estmated dccl1nc 1n water leve l from predeve l opment condlt i o ns {1880) to 1980 1n southeast Georg1a a nd adJacen t parts of Flonda and South Carollna . The U.S. Geol091ca l Survey' s ground - water data fo r Georg1d report, pub l 1shed a nnu ally s1nce 1977, des~nbe~ water con d1t 1ons 1n t he State and 1nc lud es potent1ometr 1c maps fo r the Flo n da n aqu 1fer system. An extenslve 11st1ng of these and othe r reports thut present potent 1ometnc maps for the Fl orldiln H ln ~l ud ed 1n the repor~, '";round-1~at er data for Georg1a , 1985 {Cl arke a11d others, 1986).
UPPER FLORIDAN AQUIFER
Tne Upper Flcr1da n aqu1fer 1s part of a reg1cnal ~.; ater becrlng un1t called the Flonda n aqu1fer system, WhH:h cons1sts of un1ts of l1mesto oe, dol om1te, and calca r eous sand of pnmarl l j Eocene to ~~ 1 ocene age. Near 1ts outcrop area, the Upper Flo r 1dan 1s ma1nly cl ast1 c a nd cons1sts of sand , gravel, ano clay . Oownd 1p, the a qu1fer 1s domnilntly carbonate and cons1sts of l 1mestone a nd dolom1 te . The Upper F1ondan aqu1fer 1s mos t product1ve downdlp where 1t 1s th1ck es t ilnd d1sso l ut1on cf the 11m esto ne has resu lt ed 1n seconda ry permeab1l 1ty, ln th1s area, y1elds o f as much as 10,000 ga l /~ l n and t r ansm1SS 1v1t 1es of 1 ,000,000 ft2fd have been re~Corted,
The Upper Flondan aqu1fer 1s at or nea r l a nd surface along a narrow bund that extends f rom Cl ay County northeastward to R1rhmond Co1nty. The aqu1fer d1p s end th1ckens t c the south ea st, where 1t n~aches a max1mum th 1ckness of about 500 ft 1n Glynn County. The Upper Flondan 1s confined :tbove by the clayey Hawthorn Formation and below by the c 1 ayey Llsbon Format1o n.
POTENT IOMETRIC SURFACE AND
WA TEA-LEVEL TRENDS
The Coustal Pla1n of Georg1a was d1 nded 1nto follr hydrolog1c a r eas for d1sctJss1on of the con f 1gurat1on of t he potent1ometr1c surface and \liater-level fluctuut1ons J.nd tre nd s Th ~>y are the so uthwest, sauth~central. northeast , and coa~tal areas shown 1 n the f1gure. A d 1Scuss 1on of eac h of the areas follo~s th 1s sect 1on.
The Upper Flondan aqu1fe r 1s recharged by prec1pllat1on along 1ts outcrop be l t 1n the no r theast and southwest areas where the over ly1ng con f1 n1 ng bed 1s th1n or ubsent , al l ow1ng the 1nf1ltrat10n of prf'r:1p1tat10n. In the south -cent'"al area ne <:~r Valclostil, the aqu1fer 1s recharged by streamflow that enters the aqu1fer from the W1 thl acoochee RlVer (Krause, 1979). The potent1ometr1c surface generally is highest fn recharge areas and lowest 1n d1scharge ar eas . CJnseqllently, ground water flows from a r eas of rec harge to areas of d1scharge ,
The Gulf Trough 1s a featJte that s1gn1f1cantly affer:ts the grollnd -water f1ow syst em a11d, hence, the potentlometnc surface (Kra use and Hayes, 1981). The Gulf Trough conta1ns f1ne sedments of lo w transm1ssn1ty and exte nds 1n Georgld from Decatur Cou nt.] northeast ward to Bullock Count,}. The Gulf Trough adversely affects the gro und -water flow system, as ev 1denced by l ow well y1e l ds, low transmlSS l vlty , h1gh d1ssolved-sol1ds concentrilt10ns , and a steepened potent1 ometnc gradl ent 1n the Uppe r Flondan aqu1fer as descr1bed for Colqu1tt County by Zlmmennan (1977). Th 1s steepened potent1ometr1c gradle nt 1s s. hoNn on the map , particularly 1n the area between tne 60-ft and 120-ft con: our s 1n the eastern half of the Coastal Pl a1n, and betwee n the 70-ft and 210-ft contours 1n the south-centra l part,
The conf1gurat1on c f the potent1ome tr 1c surfa ce 1s s1gn1f1Cantly dlfferent LipgradlPnt and downgra d1ent from the Gu lf Trough. Down9rad1ent from the trough, 1n the south- cen tral a nd coas tal a reas, the tran sm1ss1v1ty o f the Upper Flondan ctqu1fer 1s h1gh and t he potent1011etnc surface I S re lat1 vely flat, exc e pt near maJo r pump 1ng cen t ers 1n the coastal area and near the recharge area at Valdosta . Up g rJdlent froT'l the trough , 1n the so ut hwest and northeast areas , the trnnsmiss1v1ty of t he aqu1fer 1s lower, the aqu1fer 1s l ess co nf1ned, and the conflg urat10n of the potent1ometr1c surface 1s contro lled ma1nly by recharge fran prec1p1tat1on and d1 sc harge to streams . Rec harge occurs pnmanly 1n 1nterstream a:reas and 1s 1nd1cated on the map by co ntours that bend downgradtent. n1schargP to streums 1s shown ty con tou rs that bend upstre am, 1nd1cat1ng that thP potent1ometr1c ]rad1ent 1s toward the stream Although the potent1ome t r 1c su r face upg r adlent from the Gulf Troug h 1n the northeast area 1s largely unaffected by pum page of mare than 275 Mg<1l/ d 1 n the coasta l area, John ston and others {198 1) s uggest that the rad1us o~ l nfl uence of the cone o f depress 1on a t Savannah may have crossed the trouoh west-northwest of Savannah .
Water - level fl uc tuat1ons and trends 1n the Upper Flondan aqu1fer are shown by hyd r ographs for wells cons1dercd representat1ve of cond1t fons 1n each hydrologlc area. Cl 1matol og1c co ndltl o ns are shown by graphs of the CllmulatlVe departure of pree1 p1tat 1on at Nat10na l loleath~r Servtce stat1ons 1n each hydrolog1c area and a r e based on normals for the per1od 1980-85. Cl1mato l oo1c data 1nd 1cate that w1th the except10n of U1e south- ceiitral area. the ~1ay 1980 po t entlomet n c surface (Krause and Hayes , 1981) generul l y 1s
r epresentat1ve of a per 1od of above -n ormal prec1p1ta t1 nn,
where as tne t1ay 1985 sur fa ce 1s r epresentatlV e of a penod

o f be lol'1- no r ma l prec 1p1tat lon. The rcnn fa11 de f 1c 1t ln 1985 and the result1ng 1ncreas ed pum p1ng frcm the Upper F10r1 dan aqu1fer result ed 1n a lower water level 1n 1985 tha n 1n 1980 over muc h of the Coasta l Pla1n,
SOUTHWEST AREA
In the soe~thwest area, compnsed large ly of the Dougherty P1iJ 1n, the Upper Flondan aq u1 fer 1s less han 250 ft thlck, lS co1ered over most of the area by 25 to 125 ft of sandy -cl ay res1duum, and loca l ly 1s hydrau l 1c~ lly co nn l?ctod to the streams , In t1 1s area, the conf1gurat1on of the ~o ~e nt 1 om etr 1 c surface 1s lar gely controlled by recharge from prec1p1tat10n 1n 1nterst r edm areas and by d 1scharge to streams. Southeast of th1s area , the potent1cmetr1c grad1ent steepens 0111ng to the effects of the Gulf - rough.
Uunng 1980, an annual average ot 210 llgal/d was wllhdrawn
from th e Upper rlor1dan e.qu 1re r 1n the So .Jthwest area, pnman l y fo r 1rnga t10n Thi S large w1t1drawal, more than 2,250 llga l /d duri ng the 1rr1gat1on season (H. E. G1ll , U.S . Geolog1cal Survey , wntten commun ., 1g81) , has not produced a pe rman ent co ne of dep ress 1on bec au se the ~ells ar e w1de l y separated, pump1ng l s seasonal , the transrnlSSlVlty of the aqu1fer 1s h1gh, and recharge 1s plent1fu l dur1 ng penods of normal ra1nfe.ll,
The curnulat1ve departure of prec1p1tat1o n at Nat i onal ~leather Serv1ce sta t ion, Albany JSE , 1nd1cates that ra 1nfal1 dur1 ng 1g80-85 gene rally was bela~ normal, As a result athe def1 c1e nt r a 1nfa l l and 1ncreased 1rr1gat1on pump1ng , the gro und -w ater level 1n the Upper Flondan aq u1fer over most of thP southwest area decl1ned . Water-l~v~l fluctuat1ons 1n the southwest are a du nr g 1980 -8 5 are typ1f1ed by the hydrog'"aphs for well 13L001 1n eastern Dougherty County and well 05G006 in southern Ea r ly Cou nty . At bot h wells, the seaso nal fluctuat10 ns 1n wuter level are reflected by u h1gh dunng th e ra1ny seas cn 1n the w1nte r a nd Puly spr1ng, and a low 1n the autllmn a nd early '1nnter f o l l ow1ng the 1rr1gat 1on seasC~n. The hlQ h water level d un ng wlnter spn nq 1S85 c.t Nell 13L003 wa s lo wer t~Jan that fo r 1980 , 1983 , and 1984, and at we ll 06GC06 was lower than that f:H any of the other 4 years. Th1s 1nd1cate~ that the wlntersprlng ralnfull was 1nsuff1c1ent for the ground ~ water lev el tJ r eco\er f rom the nr1 gat1on sea son pump1ng. Recoro lo 1~ wa:er levels were measured at both \'fells 1n December 1981 , as a re sult of be lo w-n orma l prec 1 p1tat1on an d 1ncreased
1rngat1on pumpln~ . As a re s ult of th1s ra1n fal l def1c1t ,
the water level at both wells was l ower 1n /1ay 1985 than 1n May 1980.
SOUTH-CE NTRAL AREA
In the sout h-central area , the conf1gurat1on of the potent1ome tnc surf ace 1s 1n f l uenced pnmar1ly by r echarge at tile rate uf about 70 t1gal/d from the \llthlacoochee RHer near Valdo sta (Krause , 1979) . The recharge area l S shown on the map as a hlgh 1n the potent1ometr1c surface near Valdos ta . Between the h1gh at \aldosta and the coustal <Jrea, tne potent1ometnc gr ad1ent 1s l ow, pr1man l y bf'C il llse the transmlSS l vlly of the i1qll l fer 1s h1uh and there 1s l1ttle pump 1ng 1n that a rea,
Ocpress1o ns 1n the potc n t 1omctr l c surface caused by local pump1 ng have form ed at Thomasv1lle , Thomas County , e,tt,_. Hazlehur st , J eff Cav 1s County, where 1900 rllthd '"a v;al s from the Upper Fl or1 dan aqulfer were 3 .5 r~gal/d and 0.4 1~9il1/d, respect1vely (P1erce and others, 1982) . 1n the upgrad1ent part of the south-central area, tne po:ent 1orretnc surfac" s hows a steepe ned gr ad1ent ow1ng to the e f fects of the Gulf Troug h,
The cum ll atlte departu r e Jf prec1p1tat 1o n at Nat10nal lJeather ServlcP sta t1o n, Jaldosta 3E, 1nd1cates .._hat w1th the excep t 1on of 1984 , ra 1n fal l 1n the south-ce nt ra l area was below normal dur1ng the penod 1980- 85. ~lthough rainfall was below normal du r1 ng 198C ~ 85 , t1er e wc.s l 1ttle water-level decl1nc over most of the south- cent ral area. The lack of dec l 1ne can be attnbuted to the hlgh transm1>Slvl ty of the aqu1fer and lltt le P-r1 gat 1on pump1 ng 1n the area. Typ1cal water-level fluctuat1ons ond trends 1n the south - central area are shwn Uy hydrographs f or well 190!'9 at Valdosta , and wel l 17K001 at T1fton . From 1!ay 1980 to May 1985, the water level at the T1fton well decl nej a bout
10 r t, most of wh1ch occurred as a result of the 1980~81
droug ht . Although the d l f ference 1n water leve l measu r ed 1n 11ay 1980 and !1ay 1985 1s about 15 ft ct th e Valdosta we ll, the 5- year trend 1s comparatHely unchanged. At both wells, seasonal water ~l evel fluctuat10ns a r e r eflected by tngh water levels dunng the spnng ra1n,} season. The lo.~est seasJ nal water l e vel occu r s dunnq the fa l l 1n the Valdosta area , an d dur1n g the summ er 1n the T1fton area. A record low water level was me a sured at the Valdo~ta wel l 1n October 1981 and at the T1f tcn well 1n JJly 1981 . The r eco rd low ..,rater leve l < 1n the two wel l s ocurred at d1fferent L1mes of the year , becau:.e the Valdosta a r ea well lS l ocated near a s1te where stream water recharges the aqll1fer ar:~d thu s 1s 1nfl ue nced more ty st r eanflow, whereas the T1ft on ,.,el l 1s affected ma1nly by local pump 1ng.
NORTHEAST AREA
The conf l 9urat1on of the potent1ometr1c surf ac e 1n the northeast area 1s I nfluenced Hl the upgrad1ent part by r ec hc.rg e from prec1p1tat1on and by d1sch<1rge to s '"reams , and 1n the downgrad1ent pdrt by the Gulf Trough. Ar eas of recharge gene ral ly correspond to 1nterstrea111 areas . 01scharge occurs 1nto ~aJor ga1n1 ng st reams 1nclud1ng the Ocmulgee , Oco nee . a nd Ogeechee R1vers . The effec:s of the Gulf Trough on the ground-water flow system IS reflected by a steepened potent10metnc grad 1ent 1n thE southeastern part of the area .
A small depress Jon 1n t he potentwmeLnc surface fanned as a re sult of local pump1ns: at Claxton , Evans County, wh;>r e 1980 wlth dra wal s were atout 0.3 f~gal/d. ~1n cent l1982 ) reported that a cone of depress1on developed at Sandersv1l le, 1-/a~hl n gton r:ounty, d1Jr 1ng the 1940 ' s as a result of local pump1 ng , Howev er , mea s urenent s ma::le du r 1ng llay 19E 5 Jndlc i:te that th1s cone no longer 1s present because pump1ng from the aqu 1fe 1 system a t Sande rs v1lle has been dlscont1n ued.
The cum ul atf~e dep artu re of prec1p1tat1on at flat1oral Weather Se1v1ce stat1on , Dub ll n 35, 1nd 1cates t hat rainfall 1 n the nor theast area was above normal In r.,ay 1980 and helow norma l frorr the en d of 1980 through Cctober 1585 . Although ra1nfall wcs belo~1 normal dur1n g th 1s penod, the water level showed l1tt l e decllne o'o'er most of the northea st area. The la ck o~ dec l 1ne may be attr1 buted to llttle 1rn gat10n pump1ng 1n the area, llater-level flu ctua t1on s a nd trends 1n the northeast areil are typ1 f1ed by the hydro9raphs for wel l l'ITOO I l n west~rn Laurens Co unty and well 250001 1n southern f1ontgome ry County . Seasonal varldt l 011S at eac h we l l are reflect ed by h1gh wat er le \ els dur1ng the late WHiter - early spr1ng rinny season , and by lows dunng the sumer and fall, A record loN water l evel was mei!sured at we ll 25Q0011n October 1981 . Our1ng the 5- year perlod, th e water level 1n well 2JT01)1 showed no trend, whereas the wa t er l evel 1n well 250001 decllnE>d about 3 ft <'~Sa result of the ra1nfall def1c 1t,
COASTAL AREA
In the coastal area of Georg1a and ad J acent parts of Flonda und South Carol1na , the potent1ometr1c s urface 1s c haractenzed by a senes of coalesc1ng cones of depression caused by lc.rge t'ilthdrawals from the Uppe r Flor1aun aqu1fer. Abcut 275 tlgal/d 1s w1thdrawn fran the df'1 Lt1 fer 1n the coastdl arec. of Georg 1a . t1aJor pumpwg ce 11 ters 1nclude the Sava nnah , Jesup , Brunsw1ck , and St Marys, Ga. - Fernand1na 3each . Fla , areas. With the exce ption of the Sa vannah area , pumpHg 1n the$e areas 1s ma1nly for 1ndustnal Sllp ply. In the Savannah area, pump1 ng 1s about evenly d1v1ded

LOCATION OF HYDROLOGIC AREAS

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between 1ndus tr1al and publ1c supply. As o. result of th1s pump1 ng, t he ground-water level ha~ deC ll nPd s 1gn1 f1cant l y below predevelopment leve l s . For exanple , the wa t er level at Savannah has dec l1n ed mo r e than 150ft s1nce pump1ng began 1n the late 1800's (Krctuse end oth:ers, 1984).
Desp1te sim1lar rates of 111thdrawal , the s1ze of the ca ne of depress 1on at Savannah 15 51gn1f1cantlt larg er than 1n ot her parts of the coasta l area because the tr a nsm1ss1v 1 ty o f the aqu1fer at Savannch 1s lower tho!tn 1n the o ther areas {Krause and HHPS , 1981l. For exa mple, Wa1t anc Gregg (1973) r epor ted that the transm1Ss1v1ty at Brunsw1ck was f rom 107,000 to 134 ,000 ft2/d, whereas Counts a nd Donsky ( 1963) reported that the average transm1ss1v1ty at sava nnah lia s abcu t 33 ,0 00 ft<:'jd,
Because the Upper Flo r1dan aqu 1fer 1n the coastal area 1S deeply burled anc fH from the outcrOIP area, the ground dater level 1s not d1rectly 1nf l uenced by current {.985) prec1p1tat10n. The water level 1s , howe'ler , affected by 1nc r eased W1thdrawals dunng hot . dry per1ods, Hot , dry penods are refl ecte d by record s cf th e r: umul at1 ve departur e Of prec1p1tat1on at Nat1onal \le ather Serwlce stat10n, Savannah ~JSO A.P. Ra1nfall 1n the coastal area was sl1~htly abov~> normal 1n 11ay 1980, below no r mal f rrom June D80 thro Jgh Febru<1ry 1983, above uormctl from February 1983 thro1gh March 1985, and below no r mal from 1\arch through Decebe r 1985 .

In most of the coastal area , t he water level 1n the Upper Flor1dan aqu1fer showed l 1tt1e change dunng 1980- 85 , and rose 1n several areas. In 1G82, the wat2r level 1n the 8runsvn ck are a rose as mu c h as 15 rt os ill. r es.rl t of a rEduc tlOn 111 pump1ng by a maJor water user.

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1980

' 1 931

1982

1983

1984

1985

SAVANNAH AREA
Th e c o~e of depr ess1 on at Savannah cov ers an area that lncludes Chatham County and parts of Sryun, L1berty , and Eff lnghilm Count1es , Ga and adJacent pcrts of Sout h Carcl 1no. Dur1ng 1984 , about 70 J1g al/d wa s ~1thdr a wn frorn the Upper Fl ondc.n aqu1fer 1n the Savannah area, pr1mar1l y for 1ndustr1al and mu n1c 1pal use. In th1s area , smalle r cones of de press1on occur at R1ceboro as a result of
1ndustr1al pump1ng, and at Sava nna h Beach as a result of
pump1n g for publ1c supp ly ,
Water- l evel fluctl1ut1ons and trends dur1ng 1980-8~ near the center of pump1ng 1n the Savannah area are typ1f1ed by
well 360003. As a result of 1nc r ease d pump l ng due to the
1980- 81 drought, a reco r d l oN water leve l was measured at t~e wel l 1n August 1980 . A decrease 1n pu"J p1ng dur1 ng 1981-83 all o~<~ed the water level to recover from the rec ord low of 1980 . The water level showed a downward trend dunng 1983- 85 , but for the 5- year per1od, only a sl 1ght do wnward t ren d 1s e v1 dent
JESUP AREA
The so .rth east -t rend1ng co ne of depress1on 1n the Jesup area cove rs part of 1,./ayne and long Count1es along the Altamaha R1ver . Ground-water l'nth dra wal 1n the Jes up area averages 70 t!ga l /d.
The ground - water le1el 1n the Jesll p area showed l1ttle
cfJdnge dunng 1980- 35 . Although a record l o~>. wat er 1Pv~> 1
was measured 1n Jun" 1981, the hydro gr<1 ph for wel l 30 l00 3 shows o negllg1ble trend from May 1980 to r~ay 1985. In 1982 , t he o'later level rose H I response to a genera l reduc ~ t1on 1n reg10na l pump1ng ow1ng to cessat10n of the 1980 - 81 dro ught. The sp 1kes 1n the hyd rograph re present reduc t10 ns 1n 1ndustnal pump1ng near Jesup .
BRUNSW ICK AREA
The cone of dep r ess1on at Brunsw1ck. covers. a11 area that l 1es completely w1th1n Glynn County. Our1ns 1984, an est 1 11ated 80 ~1galjj was w1thdraw1 from the Upper Flo ridan aqu1fer 1n the BrtJnS\IlCk area, pnmanly for 1nd ustnal use,
The water level 1n t he Upper Flor1da n 1n most :Jf the Brunsw1ck area rose dunng 1980- 85. /l. typ 1cal water - lPtel trend near the center of pump 1ng at 8runsw1ck 1s shown by the hydrograph for well 33Hl33. Dunng 1980- 85 , the wa te r
level 1n the wel l re co ve red about 6ft largely as a result of an est1mated 10-11gal/d reduct1on 1n pumpa9e by a maJor
ind ustrial water user. ThlS pumpage reduct10n 1s reflected by a 10-ft water-level recovery dunng 1ga2. Th e sp1kes on the hydrograph are cilus~!i hy temporary shutdowns 1n 1ndustr 1al pump1n9,
ST MARYS-FERNANDINA BEACH AREA
Ground-water Wl thdrawo l s o f about 31 Mgal/d at St Marys, G<1,, and about 44 Mgal/d at Fernandlna Beach , Fla., have resulted 1:1 the format1on of a northwest-trend1ng cone of depression 1n the Upper Flondan aq u1 fer.
Our1ng 1980 ~85, the ground-wat er le ve l 1n the S+ MarysFernand1na Beach area sho~ed a Slight decl1ne. \later - level trends ln the a r ea are typ 1f1ed by the hydrograph for wel l 33E027 at K1ngs Bay Navy Base. ln February lgs_ , the wat er
leve l 1n the we l l re eched a record low as a result of
1ncreased re g1ona l pumplng. Dec r eased re~1onal pump1ng as a re sult of the cessa t1 o n of the 1980- 81 drauqh t allowed the water level to recover from the rec ord l ow of 1981. Ounng 1993, the wat er level sho we d llttle change a nd dunng 1984- 85 1t showed a decl1 ne 1n response to 1ncreased pump1ng at a nearby supply well. A record l:~w water level was measured 1n Jun e 1985.
SELECTED REFERENCES
Cl arke, J S ., and P1erce , R. R , 1985 , Georg1a water facts-groun :l water resour ces , 1n U. S. Geolog1cal Sur; ey, Nat10nal Wat er Summary , 1984 U. S. Geolog1cal Surve:,. Water-Supply Paper 2275 , p. 179-1 84 .
Cla rk e , J S , ,1o1 ner, C. N , Lo ngs .mrt h, S. A. , McFa~de n, K. W. , and Peck, M, F. , 1986, Ground - woter data for Georg1a , 1985 U.S Geolog 1ca l Survey Open -F1 le Report 85-304 ' 159 p.
Co unts, H. B and Da nsky . El llS, 1963. Salt-water encroachment , geology , and gro un:l-water resources of Sa\annah a rea , Georg 1a and So ut h Carol 1na U. S. Geolog 1ca l Surv ey Wo!tter - Supp ly Paper 1611, 100 p.
Hayes , l. R., Masl1a, 11, L., and Nee~s , W. C., 1983, Hydrology and mode l evaluat1on of t he pr1nc1 pal a rtes1an aqu 1fer, Dougherty f>l a 1 n, southwest Georg1 a Georg1 a
Geolog 1c Survey Bullet1n 97 , g3 p.
Krause, R. E., 1979 , Geohydrolog.} of Brook s , Lowndes, and o.~e s t ern Echo l s Count1es, Geor~ 1 a U.S. Geolog 1cal Survey Water-Re~ou r ces. Invest 1 gat1on~ 78 ~ 117, 48 p ,
Krause , R. E. , a nd Hayes, L. R., 1981, Potenttometr1c surface of the pr1 nc 1pa 1 artcs wn aqu 1 fer 1n Georg1 a, May 19\lll Georg1a Geo l oglc Survey Hydrologic Atlas 6, scal e 1 1 , 000 ,000.
Krause , R. E., Matthews, s. E. , and G1ll , H. E., 1984 ,
EJdluat1on of the ground-water r esources :lf coastal Georg 1 a--Prel1~1nary report on the data ava1la ble as of Jul y 1983 Georg1a Geolog1c Survey I nformat1on Cwcu l ar 67 55 p.
Krau~e . R. E., and Randolph , R. B. , 1ga7 , 1-lydrology of the Flon dan aqu1fer system 1n so uth east Georg1a a nd adjacent parts of Flor1da a nd South Carol1ne U. S. G~>olog1cal Surve.J Profess1onal Paper 1403-0 (1n press),
Johns t on , R. H., Healy , H. G. , and Hayes , L. R 1981 . Potent1ometr1c surface of the Tert1ary l1mes ton e aqu 1fer system, Southeastern Um ted St~tes, May 1930 U.S . Geolog1cal Survey Open-F1le Report 81 -486, 1 phte, scale 1 1,000,000.
Johnston , R. H., Krause, R. . , r~eyer, F. W., Ryder, P. 0.,
T1bbals, c. H. , and Hunn. J . 0 ., 1980 , Est1rJ ated
potcnt1ometnc Sllrfacc for the Tert1ary l1mestone aqu1fe,. system, Southeastern Un1ted States, pr1 o r to
development u.s. Geolog 1cal Survey Open- F1le Report
80-406, 1 p l at~ . sca l e 1 1,000,000
M1ller, J . A. , lg8?, Geo lo gy and conflgurat10n of the top of the Tert1ary 1 1m es ton e aqu1 f er system , Southeastern Un1t ed States U. S. Geolog1cal Surve y Open F1l c Report 81-1173, 1 sheet sca le l 1,000,000 .
P1erce, R. R., Barber, N l., and St1 l es, H. R , 1982, l~ater us e 1n G.:org1a JY co ur Ly for 1980 GeorgH Geologl~ Su,.\ey Informat1on C1rcula r 59, lBD p
V1ncent , ~. R., 193 2 , Geohydrologj of the Jacksoman aqu1fer 1n central and east ~ ce ntr al GeorgH Georg l t: Geolog i C Suney Hyd rolog 1c Atlil s 3 , 3 sheets.
Vla1t, R. L., a nd Gregg, D. 0. , 1t,17 3 , H:,drology end chl und e contam1nat1on of the pnnc1pal artes 1an aqu 1fer 1n Gl:,nn County, Georg1a Georg 1a Geologic Survey Hyd ro l C~glc Report 1, 93 p.
Zmmerman, [ , 0, . , 19i7, Ground-wat er resources of Co lqu 1tt r:m1nty, Georg1a U.S Geo logi cal SurJey Open-F1le Report 77~56, 41 p,

Base f r om U.S. Geolog1cal Survey St ate base map, l: 1,000,000, J 9 70

Ca r tog r a p hy by W rll1 s G. Hester

POTENTIOMETRIC SURFACE OF THE UPPER FLORIDAN AQUIFER IN GEORGIA, MAY 1985, AND WATER-LEVEL TRENDS, 1980-85

By John S. Clarke
1987