Water quality and agrichemical loading in two groundwater basins of Illinois' sinkhole plain

44 Pages·2003·3 MB·English

by  Panno, S.V

QfuJiSiXXXXi^
Water Quality and Agrichemical
Loading in Two Groundwater Basins
of Sinkhole Plain
Illinois'
S.V. Panno, W.R. Kelly\ C.P Weibel, I.G. Krapac, and S.L. Sargent
Illinois State Geological Survey and Illinois State Water Survey
Environmental Geology 156 2003 ff-^
Rod R. Blagojevich, Governor ^0^
Department ofNatural Resources
Joel Brunsvold, Director
ILLINOIS STATE GEOLOGICAL SURVEY
WilliamW.Shilts, Chief
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Cover: (Upperleft) Thestream monitoringand watersamplingsystem on theSouth Fork Creek
bridge. (Lowerleft) CollierSpringunderfloodconditions. (Centerright) CollierSpring, a circular
featureand theheadwaters ofSouth Fork Creek, isalso the resurgenceofa caveorconduitsystem
that, atsomepoint,flows beneath Fogelpole Cave.
EditorialBoard
JonathanH. Goodwin, Chair
MichaelL. Earnhardt DavidR. Larson
B. BrandonCurry JohnH. McBride
AnneL. Erdmann DonaldG. Mikulic
William R. Roy
ILLINOIS
DNEPAARTTTUWRENATOLF
RESOURCES IllinoisStateGeologicalSurvey
Printed by the authorityoftheState ofIllinois PRT3291907 - .8M - 3/03
©Printed on recycled and recyclable paperstock.
Water Quality and Agrichemical
Loading in Two Groundwater Basins
of Sinkhole Plain
Illinois'
S.V. Panno, W.R. Kelly\ C.R Weibel, I.G. Krapac, and S.L. Sargent
Illinois State Geological Survey and Illinois State Water Survey
LIBRARY.
Environmental Geology 156 2003
Rod R. Blagojevich, Governor
Department ofNatural Resources
Joel Brunsvold, Director
ILLINOIS STATE GEOLOGICAL SURVEY
WilliamV^.Shilts, Chief
615 E. Peabody Drive
Champaign, Illinois 61820-6964
217-333-4747
Home
page: http://www.isgs.uiuc.edu
Contents
Abstract 1
Introduction 1
Objectives 2
GeologyandBasinHydrology 2
Methods 3
GroundwaterBasins 3
Bridge Site 4
Indian Hole Spring 4
CollierSpring 5
Sampling 5
Analyses 6
ResultsandDiscussion 9
ChemicalCompositionofSurfaceWaterandGroundwater 9
IndianHole and CollierSprings 12
SouthForkCreekBridge 14
Agrichemicals 14
Nitrate 14
Nitrate Background 18
Phosphate 19
Pesticides 19
—
Mass LoadingCalculations StreamFlow 20
—
Mass LoadingCalculations ^Agrichemicals 20
Water-borne Bacteria 21
Dissolved Organic Carbon 22
SoilErosion Rate 22
Atrazine on Suspended Solids 22
SummaryandConclusions 23
Acknowledgments 24
References 24
Appendix 29
Tables
1 Thedrainageareas ofthe Fogelpole Cave and CollierSpringgroundwaterbasins
asdetermined frommaps andusingGIS techniques 4
2 Land use intheCollierSpringandFogelpoleCavegroundwaterbasinsandthe
total areaofthosegroundwaterbasinsplustheareadrainedbetweenthe springs
and the South ForkCreekbridge 4
3 Field parameters, ions, bacterial indicators, and herbicides forCollierand Indian
Hole Springs and the bridge across the South ForkofHorseCreek 13
4 Relationshipsbetweenspecificconductanceandmajorionsandsuspendedsolids
usingsimplelinearregression 14
5 Bacterial species isolated from watersamples collected from Indian Holeand
CollierSprings and the bridge site fromJanuary 1997 toAugust 1998 21
6 Atrazine in aqueous andsolid phases in stream-waterandsedimentsamples
collectedin1998 atthebridge site 23
Al Complete chemicaldataforthewatersamplescollected from the South ForkCreek
bridge site 29
1
A2 Complete chemical dataforthewatersamples collected from Indian HoleSpring 30
A3 Complete chemical dataforthewatersamples collected from CollierSpring 31
A4 Nitrate and herbicide samples collected at the bridgesite usingthe automated
ISCO sampler 32
A5 Ammonium, nitrate, and herbicide concentrations in springwatersamplesfrom
KellySpring, southwestern Illinois, collectedatthepeakoffloodingjustaftera
5.0-cm rainfall event 33
A6 Bacterial dataforCollierand Indian HoleSprings andtheSouth ForkCreek
bridge site 33
Figures
1 Karstterraneofsouthwestern Illinois' sinkholeplain showingsinkhole areas,
sinkhole density, andlocationofthe CollierSpringand FogelpoleCaveground-
waterbasins 3
2 Thebridge monitoringsite at base flowand flood stage 5
3 Streamdischargeversus stream stage forSouth ForkCreek at thebridgesite 6
4 Indian Hole Springislocated atthe head ofablind valleyand isthe resurgence
ofFogelpoleCave. CollierSpring is a circularfeature and theheadwatersofSouth
ForkCreek 7
5 Contourmap ofIndian Hole and Indian Hole Spring 7
6 Indian Holedoes not flowunderbase flowconditionsbut pirateswater
fromIndian Hole Springduringperiodsofflooding 8
7 Contourmap ofCollierSpring 9
8 CollierSpringunderbase flowconditions and underflood conditions 10
9 CrosssectionA-A' showingaschematic forthe approximate location ofthe
twoseparate cave systems that drain thegroundwater basin and associated
bedrockcontrols 11
10 Trilineardiagram shovdngthechemicalcomposition ofgroundwaterfrom
Indian Hole Spring 11
1 Trilineardiagram shovingthechemicalcompositionofgroundwater from
CollierSpring 11
12 Changes in pH and temperature ofgroundwaterand streamwaterduring
thesampling period 12
13 Springand streamwaterwere typicallyoversaturated with respect to calcite 12
14 Relationship between laboratory-measured alkalinityand specific conductance
plus anion concentrations usedto calculatealkalinityforthis investigation 12
15 Relationships between Na% Ca-*, Mg-*, SO^^", CI", and specific conductancefor
all samples collected and the relationship between specific conductance
measured at Indian Hole and CollierSprings 15
16 RelationshipsbetweenCa^* and SO^^"concentrationsforall samples collected at
Indian Hole andCollierSprings 16
17 Temporal changes in silicaconcentrations inwatersamplesfrom all sites over
the samplingperiod revealsthatgroundwaterfrom CollierSpringhad ahigher
concentrationofsilicathan did Indian Hole Spring 16
18 Calciumversus Mg^* concentrations inwatersamplesfromIndianHoleand
CollierSprings shovdngtwo distincttrends 16
19 Temporal changes in Mn concentrationsinspringandsurfacewatersamples
showingseasonallyelevatedconcentrations ofMnat the bridge site during
spring 16
20 Seasonaltrends in nitrateand herbicideconcentrations inwatersamples
collected at the bridge site 17
21 Loadingofnitrate, atrazine, and alachlor; streamstage; andprecipitation 17
22 Nitrateconcentrations in combined springwaterandin streamwateratthe
bridge site 18
23 CumulativeprobabilityplotofNO^"concentrations inwatersamples fromsprings,
caves, and spring-fed surfacewaterfrom southwestern Illinois 18
24 CumulativeprobabilityplotofNO3'concentrations inwatersamplesfromdrilled
and dugwells in southwesternIllinois 18
25 Atrazine concentrations in surfacewaterattheSouth ForkCreekbridge and
stream stage duringthe samplingperiod 18
26 Relationshipbetweenspecificconductanceandthelogofsuspended solids 23
Al Meanammonium concentrations acrosstheUnitedStates in 1997showing
industrialand agriculturalinput 34
A2 Meannitrate concentrationsacrosstheUnited States in 1997 showingindustrial
and agricultural input 35
A3 Nitrate and ammoniumconcentrationsinrainfall samples collected attheNADP
samplingsite nearestthe studyareafrom 1979 through 1993 showingaseasonal
trendwith the highest concentrations duringthe springandsummer 36
Abstract western Illinois' sinkhole plain.The Thesevalues represent a 21 to 31%
m
springs are located 400 (1,300 ft) loss offertilizer N, a3.8 to 5.8% loss
In akarstarea, leachingand runoffof from each otherand form the headwa- ofapplied atrazine, and a 0.05 to
agrichemicals and animalwastefrom
ters ofthe South Fork ofHorse Creek. 0.08% loss ofapplied alachlor.The
landdominated byrowcropsandlive- Groundwaterwas monitored as it dis- loss ofatrazine adsorbed onto the sus-
stockcan rapidlycontaminate ground- charged from Collier and Indian Hole pended solid fraction was low relative
waterwith nitrogen (N), phosphorous Springs and at a monitoring station to the mass ofatrazine in solution
(P), pesticides, bacteria, and soil. Dis- (a bridge) downstream ofthe springs. and amounted to only about 2 kg/yr
chargeofcontaminated groundwater Water quality analyses and stream dis- (4 lb yr) or 5.1% ofthe total mass of
fromgroundwaterbasinscan contrib- charge measurements were used to atrazine discharging from the ground-
uteto thedegradation ofwaterquality calculate the total quantityofselected water basins. Phosphate concentra-
in surface streams and, ultimately, agrichemicals (NO^ -N, PO^' and her- tions in waterwere typically less than
coastalareas.To understand the pos- bicides) (mass loading) being,carried 0.01 mg/L, suggesting that the loss of
sible extent ofcontamination in one out ofthegroundwaterbasins to sur- dissolved Pwas insignificant.
karst region, we monitored two ground-
facestreams.
waterbasins in Illinois' sinkhole plain Bacteria identified in the springwater
fromOctober 1996toAugust 1998 The NO,"-N concentrations in water included 17 generaand species present
duringa period ofaverage precipita- samples ranged from 1.08 to 6.08 in millions ofcolony-formingunits/100
tion.Weexamined thecharacterand mg/L; median concentration was 3.48 mLofwater. Klebsiellapneumoniae,
degree ofbacterial contamination, the mg/L. Atrazine and alachlor concen- Pseiidomonasspp., Escherichiacoli,
massofatrazineon suspended solids, trations ranged from <0.01 to 34.0 and Bacillusspp. predominated.
and thesoil erosion rates oftwokarst pg/Land <0.01 to 0.98 pg/L, respec-
springs andtheirspring-fed stream. tively; median concentrations were The soil erosion rate in the study
— 0.52 and 0.12 pg/L, respectively, for all area, based on the suspended solids
The two karst spring—s Collierand sites. The two groundwater basins dis- load in the stream at the bridge (10"
Indian Hole Springs drain relatively charged approximately 100,000 kg/yr kg/yr or2.2 x 10" Ib/yr), was estimated
large groundwaterbasins (approxi- (220,000 Ib/yr) ofN as NO;-N, 39 kg/yr to be a—pproximately0.15 cm/yr (0.06
mately 19.9 km- [7.68 mi-'] and 17.8 (86Ib/yr) ofatrazine, and2.8 kg/yr (6.2 in/yr) orabout twice the rate ofsoil
km^ [6.87 mi'l, respectively) in south- Ib/yr) ofalachlor. losses in the rest ofIllinois.
Introduction growth brought on by nutrients deliv- manycases via groundwater, can
ered by the Mississippi River (Rabalais degrade the waterquality ofhigher-
Loss ofagricultural chemicals from et al. 2001, Goolsby et al. 2001). order streams and other bodies of
leachingand runofffrom croplands In addition, human health problems water fed by these streams (Rabalais et
and animal waste from livestock graz- are associated with coliform bacteria al. 1996).
ing areas can load streams and shal- (Craun 1979), NO, (O'Riordan and
lowgroundwater with nitrogen (N), Bentham 1993), and pesticides (Kelce Karst regions ofthe world are espe-
phosphorous (P), pesticides, and bac- et al. 1995). Pesticides have also been cially susceptible to groundwater con-
teria. The contamination ofground- linked to environmental problems tamination from fertilizer N, associ-
waterand surface waterwith nitro- associated with endocrine disruption ated agrichemicals, and other surface-
genous compounds went from a local and the feminization ofaquatic organ- borne sources ofN (e.g., Feth 1966,
problem in the early 1970s, to a isms, leadingto reproductive prob- Hallberg 1986,White 1988. Pasquarell
regional problem in the 1990s (Heath- lems (Colborn et al. 1993, Kelce et and Boyer,1995). In the central United
waite et al. 1993), and is now becom- al. 1995, McLachlan and Arnold 1996). States, water quality problems have
ing a problem worldwide (Hallberg The herbicides atrazine and alachlor been observed in springs and wells in
and Keeney 1993, Rabalais et al. 1996. are examined in this investigation. the karst region ofsouthwestern Illi-
Diaz 2001). Because ofthe intensive Soil cultivation can accelerate soil ero- nois (Panno et al. 1994, 1996), north-
agricultural activities in Illinois and sion and lead to transport ofsed- eastern Iowa (Rowden et al. 1993),
the portion ofthe central and mid- imentswith elevated concentrations and Kentucky (Currens 1999, Ryan
western United States drained bythe ofthese contaminants into surface and Meiman 1996). Although several
Mississippi River, N contamination streams and, in karst areas, into the investigators have measured dissolved
ofgroundwater and surface water groundwater system. constituents in karst hydrologic sys-
has become awidespread problem tems duringflooding (e.g., Ryan and
(Schocket al. 1992, Kolpin et al. 1998, Septic systems (N, phosphate, and Meiman 1996), onlya few researchers
Groschen et al. 2000, Randall and bacteria) and atmospheric deposition have conducted such studies on a
MuUa 2001). For example, some scien- (N) are also potential sources of scalewide enough to encompass the
tists have attributed the hypoxic zone stream pollution. Discharge oftheir groundwaterbasin (Rowden et al.
in the GulfofMexico to excessive algal contaminants to surface streams, in 1993, Currens 1999).
linois State Geological Survey Environmental Geology 56
1
Karst regions, such as the "sinkhole ofagrichemicals duringandjust after the characterand degree ofbacterial
plain" in Monroe, Randolph, and spring planting. For example, in 1994, contamination ofthe springs and a
St. ClairCounties in southwestern floodwaters issuingfrom a springthat spring-fed stream dischargingfrom
Illinois (fig. 1), are distinguished by drained agroundwaterbasin inthe the two groundwaterbasins. Because
numerous sinkholes, disappearingor sinkhole plain dominated byrowcrops thetwo groundwaterbasins are
losingstreams, large springs, and were sampled foUovdngthe first signif- intenselykarstified andland use within
caves (Panno 1996,Weibel and Panno icant rainfall afterplanting. Concen- the basins is dominated byagriculture,
1997).Water qualityin these regions trations ofthe herbicides atrazine and we hypothesized that discharge from
has longbeen known to be highlysus- alachlor inthewatersampleswere as these basins might represent aworst-
ceptible to contamination from sur- high as97 and 16 pg/L, respectively. case scenario forthe loss ofapplied
face activities. Because ofthe rapid However, atrazine and alachlorcon- agrichemicals to a surface stream.
movement ofwater and suspended centrations in allwell-watersamples
sediment into subsurface cave and fromthe same areawere always The secondaryobjectivewas to esti-
conduit systems in this region, the belowthe U.S. Environmental Protec- mate the rate ofsoil erosion and the
amount oftime available for purifying tionAgency's (USEPA) maximum con- potentialforthetransport ofpesticides
reactions—such as adsorption, degra- taminant levels (MCL) of3 and2 pg/L adsorbed on suspended solids out of
dation, and filtration in the subsur- (USEPA 1992), respectively. thebasins. Erosion is severe in many
face—and the opportunities forexpo- places in the sinkhole plain because
sure to them are limited (White 1988). Forthisinvestigation, theareas selected ofthe open conduits and cultivation
The contamination potential is espe- formonitoringwerethe CollierSpring practices.We hypothesized that the
ciallyacute during flood events, when and Fogelpole Cave groundwater amount ofsediment dischargingfrom
largevolumes ofwatercarryinglarge basinsandtheirdischargepoints. thesegroundwaterbasins could con-
loads ofsuspended sediment that Thesegroundwaterbasinswerechosen stitute aworst-case scenario forsoil
have eroded from cropland soil and becausetheirlanduse is dominatedby erosion in an intensivelycultivated
agriculture (predominantlycroplands), karstarea.
other sources are rapidlyflushed
through karst aquifers. andtheterrainis intenselykarstified.
Wehypothesizedthatthe resultsfrom Geology and
Further, newsinkholes maydevelop, this investigationcould representa
and existing ones mayexpand, during worst-case scenarioforthelossof Basin Hydrology
and followingheavyrains.The extent appliedfertilizerN to awatershed.The Monroe County is on thewestern
and effects oferosion in the sinkhole basinsweredelineatedviadye-tracing margin ofthe Illinois Basinwherebed-
plain are reflected in complaints of techniques (Aleyet al. 2000) andare rockdips gentlyto the easttoward the
water qualitydegradation byowners underlain, inpart, byFogelpoleCave, center ofthe basin. Here, beds ofMis-
ofprivatewells in karst aquifers. abedding-plane-controlled, branch-
sissippian age limestone, sandstone,
Ctioomnpsloafinstusspaebnoduetdhsiegdhicmoennctenitnrwae-ll wwiotrhk-otvyepre22c.a5vek(mPa(1n4nomie)toalf.m1a9p98pae)d aInndthsehwaleestleiernatpoarrtneoafrthtehecosuurnftayc,e.
watercommonlyare received bythe passages (PaulWightman, personal where calcite-rich limestone beds lie
Monroe-Randolph Bi-CountyHealth communication 1997), andwhat at ornearland surface, karstification
Department inWaterloo, Illinois, fol- appearstobe anequallylongbutinac- is adominant process.This region
lowing intense rainfall and related cessiblecave (Panno etal. 1998a,Aleyet is referred to as the sinkhole plain
floodingevents (J. Bade, personal al. 2000). Drainagefromthebasins exits because ofits high densityofsink-
communication 1994). Much ofthe throughtwo springs (CollierandIndian holes.Approximately 10,000 sinkholes,
suspended sediment in floodwaters Hole) thatformtheheadwatersofthe numerous large springs, and the lon-
ofthe sinkhole plain results from SouthForkofHorseCreek (locallyand gest caves in the state are found here
erosion oftopsoil and surficial depos- hereinreferredto as SouthForkCreek) (Panno 1996). Glacial drift and other
its (predominantlyglacial till), which, (fig. 1).Amonitoringsitewaslocated materials that overlie the bedrockin
in this agricultural region, could con- 2.4 km (1.5 mi) downstreamfromthe the upland areas ofMonroe County
tain adsorbed pesticides. Desorption two springs alongSouth ForkCreek. are relativelythin (typicallyless than
ofpesticides during sediment trans- Thestreamdrains into HorseCreek, 15 m (50 ft)), and bedrockexposures
port orfollowing deposition could which, inturn, drainsinto the Kas- are common (Piskin and Bergstrom
cause elevated concentrations of kaskiaRiver, whichdischargesto the 1975).The upland area (about two-
agrichemicals in surface streams. Mississippi River.Abridge spanning thirds ofMonroe County) is, forthe
Pinavnensotiegtatael.d(t1h9e94p,ro19b9l6e)msiniatsisaollcyiated SofouotuhrFmoornkitCorreienkgweafsfortth.esiteofmuch mcioaslttilplaartn,dc/oovrerreesdiwdiutuhmItlhlaitnoiisanovgelra--
with groundwatercontamination in lain bya layerofloess (windblown
the karst regions ofsouthwestern Illi- Objectives silt). Loess and till are easilyeroded
and form steep-sided sinkholes and
3nMo0oinsd.romoGeersoatuinncddwwReaaltnledsroalsnpadhmp1C0loeusspnrtfiirneogsmswioenvreer Tgahteiopnriwmaasrtyoodbejetcetrimvienoeftthheismiansvessti- assosnoc1i9a96t)e.d gullies (Hansel and John-
loadingofselected agrichemicals and
found to contain large concentrations
Environmental Geology 56 Illinois State Geological Survey
1
The chemical composition ofground- in this area (Panno andWeibel 1999). and Collier. FurtherworkbyAleyet
—
waterand surfacewaterin the Fogelpole Cave— the longest known al. (2000) refined thebasin boundaries
sinkhole plain (wells, cave streams, cave in Illinois lies on the northeast through the use oftracerdyes.The
springs, and surface streams) is char- limb oftheValmeyerAnticline, and its refined basin boundaries showed that
acterized as a Ca^^-HCO^'-type water, directional trend parallels the axis of the CollierSpringgroundwaterbasin
which istypical ofwaters in contact the anticline. lies, in part, to the south ofthe Fogel-
with limestone (Panno et al. 1996).The pole groundwaterbasin and that the
majorityofcaves and sinkholes in the Panno andWeibel (1999) mapped two groundwaterbasins had ashared
the approximate boundaries ofthe
sinkhole plain occurinthe calcite-rich, recharge area (fig. 1).
Mississippian age Ste. Genevieve and groundwaterbasins ofthe fourlargest
St. Louis Limestones and in the overly- knowm cave systems in the sinkhole Methods
ingsediments, respectively (Panno et plain usingsinkhole distribution, water
table elevation, and bedrocktopogra-
talh.e1s9t9u7ad)y.aSrterauicntucrleusdeinthtehenovirctihnwietsyto-f phy.This initial mappingshowed that Groundwater Basins
southeast-trendingValmeyerAnticline the boundaries ofthe two groundwater The studyarea consists oftwo ground-
and Monroe CitySyncline (Weller basins discussed herein lie parallel to waterbasins: (1) the Fogelpole Cave
andWeller 1939, Nelson 1995). These and just to the northeast oftheaxis groundwaterbasin that isdrainedby
structures and local bedrocktopog- oftheValmeyerAnticline. Both basins FogelpoleCave, which, in turn, feeds
raphyplayed major roles in the for- are boundedon the northeast bythe Indian Hole Spring, and (2) the Collier
mation ofFogelpoleCave, the Fogel- Illinois Caverns and Kruegers Dry Run Springgroundwaterbasin is drained
pole Cave groundwaterbasin, adjacent Cavegroundwaterbasins, lie within bya separate conduit system, which,
large caves and theirgroundwater the Horse CreekWatershed, and termi- in turn, feeds CollierSpring (Panno et
basins, and associated karstterrane nateattwo largesprings, Indian Hole al. 1998a,Aleyetal. 2000).Thetwo
/ T10W|T9W
MISSOURI ,' ILLINOIS A
/
1
cSSi• \\ ^v •^ Nii
1) R3S
R4S
\ "^o > __
"^A r
\ '^
' »\kX^^Indian Hole
\;\v^-^ Spring
1 1 21 mi 1 ^~/%A' - xy, Bridge
3km /
Collier
V (^ Spring %
KCx1 Sharedrechargearea V/
IH
Surfacedrainage
1
CHICAGO
k
8km
1 I I I I I I I I
Sinkholeareas
I I
Figure 1 Karst terrane of southwestern Illinois' sinkhole plain (left) showing sinkhole areas, sinkhole density, and location ofthe Collier
Spring and Fogelpole Cave groundwater basins.The boundaries ofthe groundwater basin, sampling sites, and line ofcross-section A-A'
(fig. 9) are shown on the right (modified from Panno et al. 1999, Aley et al. 2000).
linois State Ceological Survey Environmental Ceology 56
1
basins have mostlydistinct drainage Table 1 The drainage areas ofthe Fogelpole Cave and Collier Spring groundwater
areas and relativelysmall areaswith basins as determined from maps by Aley et al. (2000) and using GIS techniques.
shared drainage (Aleyat al. 2000; fig. 1, Area ofeach drainage^ Total area
table 1).
Groundwater basin (km^) (mi2) (km2) (mi2)
The areasofthetwo groundwater
basins aresimilar, and land use ispre- Fogelpole Cave (PC) 16.9 6.52 17.82 6.87
dominantlyagriculture.Thetotal area Collier Spring (CS) 19.2 7.41 19.92 7.68
Shared (PC and CS) 1.44 0.56
forthetwo groundwaterbasinsthat
feed the stream is37.7km^ (14.6 Shared (PC and IC^)^ 0.27 0.10
Total area of basins 37.7 14.6 37.7 14.6
mi^).Additional drainageareato the
stream (the areadrainedbetweenthe Surface drainage 10.9 4.2 10.95 4.2
springs andthe bridge) mustbe consid- Total area of study 48.6 18.8
eredwhen interpretingdatafromwater ^Area ofeach drainage is the area that constitutes a single groundwater basin, component
samples collectedatthebridge, which ofthat basin, or separate surface drainage; total area is the area that constitutes a single
lies2.4km (1.5 mi) downstreamfrom groundwater basin plus any areas that make up two or more groundwater basins (over-
thesprings.Thatareaisapproximately lapping basinal areas) and surface drainage between the springs and the bridge.
10.9 km^ (4.2 mi^) and increasesthe ^Includes shared areas ofdifferent groundwater basins. One halfofeach shared basin was
totalareato 48.6km^ (18.8mi^). added to the FC and CS groundwater basins.
Detailedexaminationofthelandusein ^IC, Illinois Caverns groundwater basin.
thebasinsshowsthatit is dominated "Because the area is shared by Illinois Caverns, only halfofthis area was used to calculate
byrowcropsand grasslands (table2). total area.
Crops includemilo, alfalfa, soybeans, ^Includes the area ofsurface drainage between the springs and the bridge.
wheat, corn, andbarley. Herbicides,
ptyrpeidcoalmliynaarnetalpypaltireadziinneAparnidlaalnadchMlaory,; 103 cm (41 in) (J. Angel, State Clima- tions, discharge measurements at the
tologist, personal communications). bridgewere as high as 44,000 L/s
the application oftheherbicideala- Thus, the period duringwhich we (700,000 gpm) (fig. 2; tableAl). Dis-
chlorhasdecreased significantlysince conducted our investigation had aver- charge and stage data (fig. 3) were
theinitiationofthisinvestigation, and age precipitation and should have fitted to apolynomial equation, which
its useisbeingphasedout. Nitrogen yielded representative loadings of yielded the followingrelationship:
fertilizeris appliedonceortwiceper
agrichemicals in the springs and
year, usuallyinthespringandfall Q = 43.86(stage) + 0.4088(stage).
stream, aswell as erosion rates.
(Panno etal. 1996). Potassiumand
(1)
phosphatefertilizersare applied as Bridge Site South ForkCreekis fed
needed (R Kremmell, U.S. Department byCollierand Indian Hole Springs. where Qis discharge inthousands of
ofAgriculture [USDA], personalcom- However, duringflooding, overland literspersecond, and stage is given in
munication 1998). flowbetween the springs and the centimeters (r^= 0.99). Stage measure-
bridge enters South ForkCreekvia ments atthebridge sitewereconverted
The average precipitationforthe ephemeral streams that onlyflow to discharge measurementsusingthis
study area, measured at Red Bud, Illi- during and immediatelyfollowing ratingcurve (fig. 3).
nois (located about 10 km [6.2 mi] majorrainfall events. Discharge at the
east ofthe studyarea), was 107 cm (42 bridgewas determined to be about Indian Hole Spring Indian Hole
in) for 1990-2000. The average pre- 125 L/s (2,000 gpm) underbase flow Spring drains the Fogelpole Cave
cipitation during 1996 to 1998 was conditions. Under high flowcondi- groundwaterbasin. The spring is a rel-
iable 2 Land use in the Collier Spring and Fogelpole Cave groundwater (GW) basins and the total area ofthose groundwater
basins plus the area drained between the springs and the South Fork Creek bridge.^
GW
Total area basins
Land use categories (ha) (acres) (%) (ha) (acres) (%)
Row Crops^ 1,214 3,000 25.0 1,214 3,000 32.2
Forest/Woodlands 1,794 4,433 36.9 1,059 2,617 28.1
Grasslands (e.g., pasture) 1,127 2,785 23.2 814 2,011 21.6
Small Grains 589 1,455 12.1 589 1,455 15.6
Wetlands and Water 115 284 2.36 73.3 181 2.0
Urban Build-up (e.g., pavement) 22.5 55.6 0.46 19.1 47.2 0.5
Total 4,862 12,014 100 3,768 9,311 100
'Land use is based on a database developed by the Illinois Department of Natural Resources (1996) and the Illinois Natural History Survey
(2000).The database described the land use in 1996 and 1997, and there were no major changes to land use during this investigation.
^Corn and soybeans (row crops) usually are rotated annually. Acreage was assumed to contain 50% corn and 50% soybeans each year.
Environmental Geology 1 56 linois State Geological Survey