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ILLINOIS RIVER BLUFFS
AREA ASSESSMENT
“ILUNOIS STATE WATER SURVEY LIBRARY COPY
IDNR ILLINOIS RIVER BLUFFS
[ CTAP AREA ASSESSMENT.
v.2
99062906
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IDNR ILLINOIS RIVER BLUFFS
CTAP AREA ASSESSMENT.
v.2
99062906
DEMCO
ILUINUIS STATE WATER SURVEY LIBRARY COPY JY 0799
ILLINOIS RIVER BLUFFS AREA ASSESSMENT
VOLUME 2: WATER RESOURCES
Illinois Department of Natural Resources
Office of Scientific Research and Analysis
Illinois State Water Survey
2204 Griffith Drive
Champaign, Illinois 61820
(217) 244-5459
1998
Jim Edgar, Governor
State of Illinois
Brent Manning, Director
Illinois Department of Natural Resources
524 South Second
Springfield, Illinois 62701
300
Printed by the authority of the State of Illinois
Other CTAP Publications
The Changing Illinois Environment: Critical Trends, summary and 7-volume technical report
Illinois Land Cover, An Atlas, plus CD-ROM
Inventory of Ecologically Resource-Rich Areas in Illinois
Rock River Area Assessment, 5-volume technical report
The Rock River Country: An Inventory of the Region's Resources
Cache River Area Assessment, 5-volume technical report
The Cache River Basin: An Inventory of the Region's Resources
Mackinaw River Area Assessment, 5-volume technical report
The Mackinaw River Country: An Inventory of the Region's Resources
The Illinois Headwaters: An Inventory of the Region’s Resources
Headwaters Area Assessment, 5-volume technical report
The Illinois Big Rivers: An Inventory of the Region's Resources
Big Rivers Area Assessment, 5-volume technical report
The Fox River Basin: An Inventory of the Region’s Resources
Fox River Area Assessment, 5-volume technical report
The Kankakee River Valley: An Inventory of the Region’s Resources
Kankakee River Area Assessment, 5-volume technical report
The Kishwaukee River Basin: An Inventory of the Region's Resources
Kishwaukee River Area Assessment, 5-volume technical report
Embarras River Area Assessment, 5-volume technical report
Upper Des Plaines River Area Assessment, 5-volume technical report
Annual Report 1997, Illinois EcoWatch
Stream Monitoring Manual, Illinois RiverWatch
Forest Monitoring Manual, Illinois ForestWatch
Illinois Geographic Information System, CD-ROM of digital geospatial data
All CTAP and Ecosystems Program documents are available from the DNR Clearinghouse at
(217) 782-7498 or TDD (217) 782-9175. Selected publications are also available on the World
Wide Web at http://dnr.state.il.us/ctap/ctaphome.htm, or .
http://dnr.state.il.us/c2000/manage/partner.htm, as well as on the EcoForum Bulletin Board at
1 (800) 528-5486 or (217) 782-8447.
For more information about CTAP, call (217) 524-0500 or e-mail at ctap2@dnrmail state.il.us; for
information on the Ecosystems Program call (217) 782-7940 or e-mail at
ecoprog@dnrmail state.il.us.
About This Report
The Illinois River Bluffs Area Assessment examines an area in west-central Illinois that
includes parts of the upper and lower Illinois River watersheds from the vicinity of
Hennepin southward to East Peoria. Because significant natural community and species
diversity is found in the area, it has been designated a state Resource Rich Area.’
This report is part of a series of reports on areas of Illinois where a public-private partnership
has been formed. These assessments provide information on the natural and human resources
of the areas as a basis for managing and improving their ecosystems. The determination of
resource rich areas and development of ecosystem-based information and management
programs in Illinois are the result of three processes -- the Critical Trends Assessment
Program, the Conservation Congress, and the Water Resources and Land Use Priorities Task
Force.
Background
The Critical Trends Assessment Program (CTAP) documents changes in ecological
conditions. In 1994, using existing information, the program provided a baseline of
ecological conditions.* Three conclusions were drawn from the baseline investigation:
1. the emission and discharge of regulated pollutants over the past 20 years has declined, in
some cases dramatically,
2. existing data suggest that the condition of natural ecosystems in Illinois is rapidly
declining as a result of fragmentation and continued stress, and
3. data designed to monitor compliance with environmental regulations or the status of
individual species are not sufficient to assess ecosystem health statewide.
Based on these findings, CTAP has begun to develop methods to systematically monitor
ecological conditions and provide information for ecosystem-based management. Five
components make up this effort:
1. identify resource rich areas,
2. conduct regional assessments,
3. publish an atlas and inventory of Illinois landcover,
4. train volunteers to collect ecological indicator data, and
5. develop an educational science curriculum which incorporates data collection
' See Inventory of Resource Rich Areas in Illinois: An Evaluation of Ecological Resources
? See The Changing Illinois Environment: Critical Trends, summary report and volumes 1-7
iil
At the same time that CTAP was publishing its baseline findings, the Illinois Conservation
Congress and the Water Resources and Land Use Priorities Task Force were presenting their
respective findings. These groups agreed with the CTAP conclusion that the state's
ecosystems were declining. Better stewardship was needed, and they determined that a
voluntary, incentive-based, grassroots approach would be the most appropriate, one that
recognized the inter-relatedness of economic development and natural resource protection
and enhancement.
From the three initiatives was born Conservation 2000, a six-year program to begin reversing
ecosystem degradation, primarily through the Ecosystems Program, a cooperative process of
public-private partnerships that are intended to merge natural resource stewardship with
economic and recreational development. To achieve this goal, the program will provide
financial incentives and technical assistance to private landowners. The Rock River and
Cache River were designated as the first Ecosystem Partnership areas.
At the same time, CTAP identified 30 Resource Rich Areas (RRAs) throughout the state. In
RRAs where Ecosystem Partnerships have been formed, CTAP is providing an assessment of
the area, drawing from ecological and socio-economic databases to give an overview of the
region's resources --.geologic, edaphic, hydrologic, biotic, and socio-economic. Although
several of the analyses are somewhat restricted by spatial and/or temporal limitations of the
data, they help to identify information gaps and additional opportunities and constraints to
establishing long-term monitoring programs in the partnership areas.
The Illinois River Bluffs Assessment
The Illinois River Bluffs Assessment covers an area of about 560,871 acres in west central
Illinois. It includes parts of the upper and lower Illinois River watersheds from the vicinity
of Hennepin southward to East Peoria. Counties encompassed in this assessment include
most of Marshall and Woodford counties as well as small portions of Stark, Bureau, La
Salle, Tazewell, Putnam, and Peoria counties. In addition to containing a portion of the
Illinois River Drainage basin (Illinois River upper and lower), this area also encompasses
portions of the Crow Creek west, Sandy Creek, Senachwine Creek and Crow Creek east
drainage basins as identified by the Illinois Environmental Protection Agency. Three of
the sub-basins in this assessment area (Illinois River lower, Senachwine Creek, and Crow
Creek east) were designated as “Resource Rich Areas” (a total of 277,847 acres) because
they contain significant natural community diversity. The Illinois River Bluffs Ecosystem
Partnership was subsequently formed around this core area of high quality ecological
resources.
This assessment is comprised of five volumes. In Volume 1, Geology discusses the
geology, soils, and minerals in the assessment area. Volume 2, Water Resources,
discusses the surface and groundwater resources and Volume 3, Living Resources,
describes the natural vegetation communities and the fauna of the region. Volume 4
rs me
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Subbasins in the Illinois River Bluffs Assessment Area. Subbasin boundaries
depicted are those determined by the Illinois Environmental Protection Agency.
contains three parts: Part I, Socio-Economic Profile, discusses the demographics,
infrastructure, and economy of the area, focusing on the three counties with the greatest
amount of land in the area — Marshall, Peoria and Woodford; Part I], Environmental
Quality, discusses air and water quality, and hazardous and toxic waste generation and
management in the area; and Part III, Archaeological Resources, identifies and assesses
the archaeological sites, ranging from the Paleoindian Prehistoric (B.C. 10,000) to the
Historic (A.D. 1650), known in the assessment watershed. Volume 5, Early Accounts of
the Ecology of the Illinois River Bluffs Area, describes the ecology of the area as
recorded by historical writings of explorers, pioneers, early visitors and early historians.
Vii
Digitized by the Internet Archive
in 2010 with funding from
University of Illinois Urbana-Champaign
http://www.archive.org/details/illinoisriverbluO2illi
Contributors
PARES COORGIN ALON <asccacusacsucevseeasaiascocaseasstoreternnser tse tovssacssessuscssesoddseuctsesssns Nani Bhowmik
|S EY a REN ee ee ee Robert Sinclair, Mark Varner
| ELOY OY, SCZ ae a Christopher Wellner
Introduction
Rivers:and streams; bakes; Physiography ict -cc.sc.s.cccceccececscescesscceecers H. Vernon Knapp
CEL ANSE 5 tesa cress susie cast ccs-veeecsesied Michael Miller, Liane Suloway, Laura Keefer’
| C5170 Ll Ub Rn eR BRR oo er ERR aS RARER ae SRR Laura Keefer
Climateiand Wirend ssn) Climate.....0:<csseccecsesseessecssesosessess James Angel, Wayne Armstrong
SSEREATITI OW aicesacocstescneccncenscececseess H. Vernon Knapp, Gana Ramamurthy, Kenneth Nichols
Erosion and Sedimentation.................. Misganaw Demissie, Renjie Xia, William Bogner
Water Use and Availability
Ground-Water Resources ..............:..0+ Kenneth Hlinka, John Blomberg, Kay Charles
SSEIACE BN ALE TIRES OUNCES sisscc: cox estoec 5, cctsas eo cacevasuattes Meet thc comets aposs- ss H. Vernon Knapp
Ground-Water Quality............eeeeeeeeee Kenneth Hlinka, John Blomberg, Thomas Holm
* Contributor Affiliations: Michael Miller, Illinois State Geological Survey; Liane Suloway, Illinois Natural
History Survey; Laura Keefer, Illinois State Water Survey.
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Table of Contents
PIITOGUICHION BI42. 30.5 Mev .c. bts Beste eee AEs. eats te eca RSI OGE Pas sake leanchigusesesedsevecusesoaneueaceecceetes |
RIVETS, ATIC S Cr emtEMISHEE Se A Seek iced RA AMER EE 595 8S Ss basen cctuessuascseseaccusecdsene l
TEAK CS): cS Rvevs the dead Bcesene Mhc ds beans enenacev Maca tetete sete nsadlsnnaseaa gi Ehlaasihcveséseseceusssesgsunscsseséce 4
DEL ATS oes ce cots aan ae ous RN po nese PAR LS acne ds suunaida div vsseuanasuentiinpaiyvaaessbedsiacsvs 5
PET VSUO STADIA pace acs as vbds dze cscs nstntenis sso tauasulteasa waka casts sudapaaed edactonsundassvaawas dass ccesedactciesdesss 10
MAAN a cit cat sui catenins Ba vcuo ot ope sae cu dat ecuvssa causes hatasatiiuetiasessbdesivesucsrassonatsbecicat: 11
Whimate ang Arenas rimgS lita ale esse ste secs cacscsusnnaesensusosesssseseenassesnandsbncs ssbsGTeese cd coccacees 13
PheMperatune css. ev sscctiweeas eta weeewes Sebecblcbsce INE tive dap Sanseeda dea Svauecate concealers Meacesccces: 13
EPG) po Mea Hite ieee eee tees hee ccc tcb tect SececBenowsddbseesnseatibendgisnstcadtienensennendeeReueatets.-s 17
BRecipitaniOn: MeniCits ANG EXCESSES sa..5c220:5cccsnaseseorostsbesvseusiiscstescessesepecsscsicanics 19
BROT VV CAL Che crce tccecccte reece ee saate css ciiics eave dsspecsusiscbsesgaSssasadnécaseedetnsiiessseeteeteatecczenvers 20
IMO TERACLOGS wenes cece eetccen es eee see cn cte sat sca aual yesesadcoedudces desstcaccessouse¥aisa tdesossonaval Obvedes 20
|S EY eo Ede ag fee nr RAS ene rere ac ee 21
siunderstorms: 5. «Ad Sess Siete: aercee edited ewes spsten, Avis ded Be es 21
STDIN) “eee asd cee ses Lantos oe ratte Seats cccsu save cease SRS eezecets detest) gepcdeacesnisccaséccovedees 22
IS Eire eATgE Es OW Pepe eens, Benes eee ee cae ame Rte 2d aR SI RUN ET gs 23
Shredmi Gagne RECOrdS s. 2is3 secs ete e-checeace a cacatt acon te otaaa sao ecngh cases eSasgeteosbbbasesacsieses 28
Human Impacts'on Streamflows)in the Basin (22.00.42. ...0.\.200252s265ssossesecesSecnsecousceee 25
Anal: Streamitlow dy ariabilit yy ee eee seek eee, 2 TS cs sccaseudsz 26
StatisticaleDrendy A tial ysis eset ccesezss, cots Mae ere eitonn seas tanesonsSetes tadstiaddinstenece tess 26
DailyandSeasonaliow Variability ascccccoscescsncsors<csseseaert dscssctatiea) csoes ch ceeevikeocsssouse 28
Pl Gein SHAR EERE SE OWS wate cs choco cakacase OM ena ue a ocuswabccchosz co eteonsence deck stsseti veshieet cxboocccsues 29
StAaliSticallBrenGyANALYSIS fs ccceceasdancse eee teicensestncrsecteckerre eeaten te oo eoek hssttoe tees 30
HHpach Ob Peoiia lake On Peak PIOWS 2 ccccecoscecscccecsaccoteereieaceseee terete susscesnsssecezoks 32
Seasonal’ Distribution Of Flood Event, .:::.5.5.202:+<c.e0vsss0sa0sus000se-denesecasueeo-essossonse 32
MOU ETAL AMG UISO WOW S cer cen ssc Sccactc sec icoci tS tes eee sauce eure dessa ceasasesoessussoauseinecereentecetese a3
SSUTIIIDIADY cess cre cecesscctencconscce te rtas set ante as et Sse RIS LO PR TO vaca REGS gp)
ETOStOT an, SCCUMeMt ARO Mts ccas car acarareers see tccenecescteaceesdan sacs Piva ecnstesosee ck dseeatbetesome ee. 37
MAsthe amped ie mead: oanes cease oceans eee eee oes atos cee eseartt tne roe eR ccsebosctconescs 3i/.
SEGUMEM ALOR acct ctecrsceccstect eet a Sees Noe ee ee TULEN ct PEIR 51
Water WsevandsAwailabilityy: 22). ie een. ete Lond tom Salen mun £ meds, 53
Grrolind-W ate te CSOUICES pet ane es ceee st Se tcasts deamon sasesescdvc Cases 53
Bata Sources ent eres: neice esas tes, Sse hace, hacsce hins. eisctet cob ade oc osebeeiek 54
Wrata PiIatOWS eset Socesten eecoecze eens Settee, ence ees e ee ee MAE SEU 54
Ground Water,Availabilitye:2 287.0. Sie 4220) 10 ce MEI Bio...) 4. ty lit 55
PODS" GrounG=W ater Use ree teas a aectecccsrae le eae de eT Se Solesctaasestenste 56
Grodud-Water Use irendse sxe Ny aienel te ide Sane he Ot gue et Si
SUWACE W aler RESUMES wie teste TM cto mata ae ssa Me a pee Be aedade ed oy
Water Use-and Availability ago. c.:0405 5 Fs tec cen Be ccsscscrsocevcceecet af,
Potential for Development of Surface Water Sources.........c.ccccscccecessseseseseseseees 58
xi
Ground-Water Quality 3.<.scs. Sesccpergt cos ct 5 Poa cccuzals eebsescutnescsnntuntenscecasivadenvenseeseaestentesies 61
Data SOUP COS secs ccisccedisdscecssessesdesdaresdecetstecdecssestetceseceoesuansdeasessacecus sragscusieacsteadeoseucsicessve 61
DEA LARCAIONS sicsasisasesneiecaanndetessecesesixscatisenssseasacescssusectansscdbsisveeasovtaieanseseabeediouszesttame 62
Chemical Components Selected for Trend AnalySis............::scssesssesesseesseeeseeees 63
Aquifer Unit AMA YSIS: ,.cissiypsccszescnsnasstecaececsassbenetestenangeaunsnssteacacessye sacenssoneceeaemeerere te 63
DiSGuSsiGn Arid RESUS... ssscdcscesséscscsscccsvesnscdesssaccbsesecesatesteledtecensecesterteeeereteceete eee aes 64
TOM (FE) .2:cccsssosscscececssacescdenascaacdaaseseasvaseswconaceceteneceskcoee acer tates aeee aan ane S eee ad 67
Total Dissolved Solids (TDS) isccc..0c2s0ccccccthecssicec ees Stat teaathsaetaeeatiot eee sees 67
SUT fate (SOs) as cssssincccccnsccacehovssensvspavecssvssopiestenstestscupekthsstuenchetes Otaas an Meee mn Rees 68
Nitrate] (INO 5) ascectscccscossoccsasseocesacceccescncecucevecabasscusdcnnecvoseyteanseeasipithintieseres me mepaaeaas 69
Chloride:(Cl) sccccsesesineccascenstsesssssnesieceanvonstnngesxvnrnsndsuaitatentedoaade ct bacnestPebpeay<amancuaee 69
Hardness: (a8 CaCO). scsccvadcsccasescessnsasansesnveceseezpseecnposstbes sccectensasnsatinearonpeetae 70
SUMISIALY wos essetsvorwsuaasisassivscasnaesusesodnutannisnespdtansaunsosdbssacnaseeaseen cles arameereneaeeeee 71
RREPOTENICES oicdccnsecachsaccsesccuccasxccccccedscavncecrosedtenvcheouh canecencsnsceseovettcte te taeomte rete et RRe aN eelsa Seteae IE:
List of Figures
Introduction
Figure 1. Major Streams and Lakes in the Illinois River Bluffs ................scscsseseeesesees 2
Figure 2. Stream Profiles for Three Tributaries in the Illinois River Bluffs Area ...... +
Figure 3. Wetlands from the National Wetlands Inventory and Quadrangle Map
Boundaries for the Illinois River Bluffs Assessment Area...............:0:cce0s0++ 8
Figure 4. National Wetlands Inventory Information from the Lacon
7.5-Minute Quadrangle Map Showing Wetlands,
Deepwater Habitats; ‘and: NWI COdEeS «.....c:.cscccusssacscnrecarcaceassenssuecsteanarsecsoreur 9
Figure 5. Acreages of Selected Crops in the Illinois River Bluffs Area
Based on JAS Data sitsieccscassscaspscensssassciscsceoccnatenteeeets stn ansnsaastashennauaeseeanee 1]
Climate and Trends in Climate
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Mean Annual Temperature for Peoria, 1901-1996 ............ecseseeseeeseeeeeeee 14
Annual Number of Days with Maximum Temperatures
Equal to:or Above 90°F at: Peoria, 1901-1996... a. ..icecc0atatpansacseseccastaaesase 15
Annual Number of Days with Minimum Temperatures
Equal to or Below 32°F at Peoria, Winters 1903-1904 to 1995-1996........ 16
Annual Number of Days with Minimum Temperatures
Equal to or Below O°F at Peoria, Winters 1903-1904 to 1995-1996.......... 16
Annual. Precipitationiat Peoria, 1896-1995........:.c..ossscasseactsarssatasrecorsrasosons 18
Annual Number of Days with Measurable Precipitation
at Peoria; 1901-1996... ...c2..csnce<ssasscassans sees eeece SE's eames coes sears ant 18
Annual Snowfall at Peoria, Winters 1903-1904 to 1995-1996..............24 19
Annual Number of Days with Measurable Snowfall
at Peoria; Winters: 1903-1904 to. 1995-199 Guise: eR ST econ 20
Annual Number of Days with Thunderstorms at Peoria, 1948-1995
Xil
Streamflow
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
Stream Gaging Stations in the Illinois River Bluffs «0.0.00... eee eeeeeeees 24
Average Annual Streamflow for a) the Illinois River,
and b) the Tributaries in the Illinois River Bluffs Area....................cccee. 27
Flow Duration Curves (Discharge Versus Probability) ...........0cc cece 28
Monthly Flow Probabilities for Crow Creek near Washburm..................... 29
Annual Peak Discharges for a) the Ilinois River,
and b) the Tributaries in the Illinois River Bluffs Area....................:..000082 31
December 1982 Flood Hydrographs for the linois River at Henry
SRI PRR GION IVAITIOS nocetessseccccccsecctecsenssnncerestscutneccotcenecsteascereessesthemeessecstersere 32
Annual 7-Day Low Flows for a) the Illinois River,
and b) the Tributaries in the Illinois River Bluffs Area... 34
Erosion and Sedimentation
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Sediment Monitoring Stations in the Illinois River Bluffs .........0..0.0... 38
Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for the Ilinois River at Chillicothe .........00..000.. 40
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Crow Creek................ 41
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Dry Creek.................. 42
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Richland Creek......... 43
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Partridge Creek......... 44
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Blue Creek................ 45
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Funk’s Run............... 46
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Tenmile Creek .......... 47
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Senachwine Creek .... 48
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Dickison Run............ 49
Variabilities of Instantaneous Flow Discharge, Suspended Sediment
Concentrations, and Suspended Sediment Load for Farm Creek ............... 50
Water Use and Availability
Figure 34.
Potential Reservoirs in the Dlinois River Bluffs..................c.ccccccseeeeeeeeseeees 59
Xill
List of Tables
Introduction
Table 1.. . Tributaries inthe:Hlinois River Blutis Area, ‘04:5. <cccigse-coasescessecssscvsdsessceraconss 3
Table 2. Significant Lakes and Reservoirs in the Illinois River Bluffs Area.............. 5
Table 3. Wetlands in the Hlinois River Bluffs Area .................csssccccccsesssseeccesssssnseeeees |
Table 4. _ Distribution of Land Slopes for Marshall County ..............:cssssssssssseseeeeeees 11
Climate and Trends in Climate
Table 5;s,,; ;,Lemperature Summary fOr PeOMd ....5.:+..:-ssesesscsateccsstacaneathssntnesecarsntxaseseneeee 14
Table 6. | Average Annual Temperature during Consecutive 30-Year Period........... 15
Table7.. Precipitation Summary for Peoria...........::sscsissassanscsseesssecsscononsvesussseesecesaaes 17
Streamflow
Table 8. | USGS Stream Gaging Stations with Continuous Discharge Records ........ 23
Table 9. | Trend Correlations for Annual and Seasonal FIOWS............:s:ccscesscesseseeeees 28
Table 10. Trend Correlations for Flood Volume and Peak FIOW ...........:..::cscesseseeees 30
Table 11. Monthly Distribution of Top 25 Flood Event .............::cscescesssseeeeeeeeeeeeeees 33
Erosion and Sedimentation
Table 12. Sediment Monitoring Stations in the Dlinois River Bluffs Area................ 37
Table 13. Tributary Streams in the Ilinois River Bluffs Area..............::cscsscssesseeeeees 39
Table 14. Annual Sediment Load for the Illinois River at Chillicothe...................2- 51
Table 15. Lake Sedimentation Rates in the Illinois River Bluffs Area....................0.5 a2
Water Use and Availability
Table 16. Number of Reported Private Wells in the Illinois River Bluffs Area......... BS)
Table 17. Ground-Water Use Trends in the Illinois River Bluffs Area................000+5 57
Ground-Water Quality
Table 18. Chemical Constituents Selected for Trend Analysis,
Uneonsolidated Systems tints cee seen sare! Bispace ee Ge codes eoueeene n= c 65
Table 19. Chemical Constituents Selected for Trend Analysis,
BedrockeAquiferms ystems icy. «..255eu stone ais: sae. saesge rain ones sane area 66
XiV
Introduction
The Illinois River Bluffs area is comprised of a 33-mile stretch along the Illinois River,
between river miles 166 and 199, and the watershed areas of all tributaries that drain into
the river in this reach. This portion of the river stretches from the city of Peoria upstream
to Senachwine Lake, north of the town of Henry. The Illinois River valley in this region
is broad, gently sloping, and contains a number of backwater lakes which provide both a
substantial recreation benefit to the region and habitat for wildlife, fish, and waterfowl.
Foremost of these is Peoria Lake, which is the largest and deepest bottomland lake in the
Illinois River Valley. The river valley in this reach is bounded by steeply-sloping bluffs,
typically rise over 150 feet above the valley floor, for which the region is named.
Progressively farther from the river, in the tributary watersheds, are upland areas that are
gently to moderately rolling. The total area of the bottomlands, bluffs, and tributary
watershed measures 876 square miles, and includes portions of seven counties: Peoria,
Tazewell, Woodford, Marshall, Putnam, La Salle, and Bureau. Figure 1 shows the
Illinois River Bluffs area and its major streams. Mean annual precipitation for the river
basin is about 36.25 inches.
Rivers and Streams
There are about 1,450 miles of rivers and streams in the Illinois River Bluffs area. Larger
streams (those with watersheds greater than 10 square miles) account for about 25% of
this total, or approximately 358 river miles.
The total drainage area of the Illinois River at the downstream end of the Bluffs area is
14,165 square miles, and represents 49% of the entire Illinois River basin. The upper
Illinois River basin extends upstream to encompass almost all of northeastern Ilinois,
including most of the Chicago metropolitan area, and portions of southeastern Wisconsin
and northwestern Indiana. Much of the Illinois River upstream of the Bluffs area flows
through a fairly narrow channel having a moderate channel slope; in the Bluffs area,
however, the river’s slope becomes very flat and the river bottomlands broaden, in some
locations to more than three miles wide. The river’s channel is naturally constricted at
Peoria, where the Bloomington Moraine crosses the river, creating a series of broad
shallow pools on the river. The Peoria Lock and Dam, 8 miles downstream, adds an
additional control that stabilizes water levels on the river during low and medium flows.
The Illinois River has four major tributaries in the area, Sandy Creek, Crow Creek (East),
Crow Creek (West), and Senachwine Creek. These streams are shown in Figure 1.
Additional tributaries having drainage areas in excess of 10 square miles are listed in
Table 1.
Scale 1:410000
0
N Basin Boundary
/\/_ Streams
Figure 1.
Major Streams and Lakes in the Illinois River Bluffs
Table 1. Tributaries in the Illinois River Bluffs Area
Drainage area Illinois
(sq. mi.) River Mile
Counties
Tenmile Creek Tazewell, Woodford 17.6 166.2
Blue Creek Woodford 10.5 173.1
Partridge Creek Woodford 28.0 177.3
Richland Creek Woodford 47.0 180.4
Snag Creek Woodford 40.6 181.1
Crow Creek (East) Marshall, Woodford 130.0 182.2
Strawn Creek Marshall 10.2 185.5
Senachwine Creek (South) Peoria, Marshall 90.0 181.6
Gimlet Creek Marshall 5.7, 189.1
Crow Creek (West) Marshall, Putnam, Bureau 82.0 191.6
Sandy Creek Marshall, LaSalle 146.0 196.2
Clear Creek Putnam 38.5 197.0
Senachwine Creek (North) Putnam 38.0 199.0
The two largest tributaries, Sandy Creek and Crow Creek (East), originate in eastern
Marshall and Woodford Counties, in an area typified by flat to gently rolling plains. The
stream slopes in this region are moderate, averaging about 2.5 feet per mile (ft/mi). The
highest land elevations in this area are generally about 700 to 750 feet above mean sea
level (msl). Figure 2 illustrates the channel slope of some tributaries in this area. As
Crow Creek flows west, the channel slope increases to a maximum of 15 ft/mi as the
stream flows past the bluff line down to the Ilinois River.
In contrast is Crow Creek (West), which originates in Bureau County and flows through
western Putnam and Marshall Counties, through the hilly topography of the Bloomington
Moraine. The headwaters on the western side of the region is almost 100 feet higher than
that on the other side of the Illinois River, and the channel slope is almost 20 ft/mi. The
channel slope decreases downstream, but always remains comparatively steep (above 10
ft/mi). The profile of Strawn Creek is typical of the many small streams which originate
near the bluff line, cutting through the steep slopes to the Illinois River bottomlands. The
maximum channel slope for Strawn Creek exceeds 30 ft/mi.
The streams in the Illinois River Bluffs area are generally well developed and incised so
as not to require channelization. Most of the channelized stream segments are near the
headwaters of Crow Creek (East) and Sandy Creek, in the eastern fringe of the region
(Mattingly and Herricks, 1991).
850
800
750
700
650
600
550
ELEVATION, feet above msl
500 Ky —*— Crow Creek(West)
d —e@— Crow Creek
450 7 a © —# Strawn Creek
400
0 5 10 15 30 35 40 45
20 25
DISTANCE, miles
Figure 2. Stream Profiles for Three Tributaries in the Illinois River Bluffs Area
Lakes
The constriction of the Illinois River at Peoria, along with the overall low gradient of the
river, creates a series of backwater and flow-through lakes throughout the Bluffs area.
These lakes and the entire bottomland area along the river are the vestiges of a larger river
system that occupied the [linois River Valley during the last glacial period.
Table 2 lists the largest of these bottomland lakes. The total water surface area of the
river and these lakes is approximately 32,000 acres, or 50 square miles. Peoria Lake,
located between river miles 166 and 182, is the largest of these lakes and accounts for
almost half of the total surface area. A well-known concern for the lakes is sedimentation
and volume loss, described later, and its impact on the ultimate viability of the
bottomland lakes.
Also listed in Table 2 are the region’s two largest impounding reservoirs, Thunderbird
Lake and Wildwood Lake, which are used primarily for recreation. In addition, there are
82 other smaller lakes in the Illinois River Bluffs area. Forty-five of these smaller lakes
are located in the Illinois River bottomlands, with the five largest being gravel pit lakes.
The remaining lakes are small impounding reservoirs with surface areas less than 30
acres.
Table 2. Significant Lakes and Reservoirs in the Illinois River Bluffs Area
Surface area
County (acres)
Peoria Lake Peoria 14,000 Backwater
Goose Lake Woodford 3,000 Backwater
Douglas Lake Marshall 973 Backwater
Goose Lake/Weis Lake Marshall 1,300 Backwater
Babb Slough/Sawyer Slough | Marshall 1,875 Backwater
Billsbach Lake Marshall 1,015 Backwater
Sawmill Lake Putnam 630 Backwater
Senachwine Lake Putnam 3,325 Backwater
Goose Lake Putnam 2,360 Backwater
Thunderbird Lake Putnam 114 Stream Impoundment
Wildwood Lake Marshall 197 Stream Impoundment
Wetlands
Wetlands are an important part of our landscape because they provide critical habitat for
many plants and animals and serve an important role in mitigating the effects of storm
flow in streams. They are also government-regulated landscape features under Section
404 of the Clean Water Act. In general, wetlands are a transition zone between dry
uplands and open water; however, open-water areas in many upland depressional
wetlands are dry at the surface for significant portions of the year.
The Illinois River Bluffs area has about 5.9% (33,206 acres) of its total area in wetlands
(Table 3). Approximately 14% (15,534 acres) of these wetlands are in the river valley
and are classified as lacustrine or shallow lake wetlands. Approximately 35% (11,595
acres) of the total wetlands exist in stream corridors and are classed as bottomland forest
or riverine wetlands. (For wetland categories, see the table describing wetland and
deepwater habitat in Volume 3: Living Resources.)
Table 3. Wetlands in the Dlinois River Bluffs Area
Subbasin Wetlands
% of % of % of total
Subbasin name Acres area Acres subbasin wetlands
Crow Cr. E. 19,850 839.05 4.2 DES
Crow Cr. W. 514125 9.1 552,91 1.1 Lif
Illinois R. lower 207,848 S741 26,443.38 12.7 79.6
Illinois R. upper 71,510 127 3,247.68 4.5 9.8
N. Br. Crow Cr. E. 19,479 355 W113 0.4 0.2
S. Br. Crow Cr. E. 42,382 7.6 270.93 0.6 0.8
Sandy Cr. 91,089 16.2 443.52 0.5 ies
Senachwine Cr. 57,583 1,336.71
Total 560,866 33,205.91
The hydrogeology of wetlands allows water to accumulate in them longer than in the
surrounding landscape, with far-reaching consequences for the natural environment.
Wetland sites become the locus of organisms that require or can tolerate moisture for
extended periods of time, and the wetland itself becomes the breeding habitat and nursery
for many organisms that require water for early development. Plants that can tolerate
moist conditions (hydrophytes) can exist in these areas, whereas upland plants cannot
successfully compete for existence. Given the above conditions, the remaining wetlands
in our landscape are refuges for many plants and animals that were once widespread but
are now restricted to existing wetland areas.
The configuration of wetlands enables them to retain excess rainwater, extending the time
the water spends on the upland area. The effect of this retention on the basin is to delay
the delivery of water to the main stream. This decreases the peak discharges of storm
flow or floods, thus reducing flood damages and the resulting costs. It is important to
realize that the destruction of wetland areas has the opposite effect, increasing peak flood
flows and thereby increasing flood damages and costs.
The location of wetlands affects many day-to-day decisions because wetlands are
considered “Waters of the United States” (Clean Water Act) and are protected by various
legislation at the local, state, and federal levels (for example, the Rivers and Harbors Act
of 1899, Section 10; the Clean Water Act; and the Illinois Interagency Wetlands Act of
1989). Activities by government, private enterprise, and individual citizens are subject to
regulations administered by the U.S. Army Corps of Engineers. Under a Memorandum of
Agreement between federal regulatory agencies with jurisdiction over wetlands, the
Natural Resources Conservation Service takes the lead in regulating wetland issues for
agricultural land, and the U.S. Army Corps of Engineers takes the lead for all
nonagricultural lands.
In contexts where wetland resources are an issue, the location and acreage of a wetland
will be information required by any regulatory agency, whether local, state, or federal.
Currently, there are two general sources of wetland location information for Illinois: the
National Wetland Inventory (NWI), completed in 1980, and J/linois Land Cover, an Atlas
(ILCA) by the Illinois Department of Natural Resources (1996). The State of Illinois used
the NWI information to publish the Wetland Resources of Illinois: An Analysis and Atlas
(Suloway and Hubbell, 1994). While this atlas is not of suitable scale for landowners or
government agencies to use for individual wetland locations, it can be used by agencies or
groups that consider wetlands in an administrative or general government manner and
focus on acreage and not individual wetland boundaries.
The NWI program involved identifying wetlands on aerial photographs of 1:58,000 scale
and publishing maps of this information using USGS 1:24,000-scale topographic
quadrangle maps as the base. NWI quadrangle maps for the Illinois River Bluffs area are
shown in Figure 3. Individual quadrangles can be purchased from the following address
(see page 7).
Center for Governmental Studies
Wetland Map Sales
Northern Illinois University
De Kalb, IL 60115
Telephone: (815) 753-1901
Digital data by quadrangle are available from the NWI Web site: www.nwi.fws.gov.
The ILCA inventory used Landsat Thematic Mapper satellite data as the primary source
for interpretation. National Aerial Photography Program photographs verified the land
cover classification and helped ensure consistency from area to area within Illinois. The
ILCA and companion compact disc can be purchased from:
Illinois Department of Natural Resources
524 South Second Street
Lincoln Tower Plaza
Springfield, IL 62701-1787
Telephone: (217) 524-0500
E-mail: ctap2 @dnrmail.state.il.us
Web site: http://dnr.state.il.us/ctap/ctaphome.htm
Although the ILCA and NWI programs were not meant for regulatory purposes, they are
the only state or regional wetland map resources available and are the logical sources for
beginning a wetland assessment. The presence or absence of wetlands as represented by
the wetland maps is not certified by either the ILCA or the NWI mapping program.
Figure 4, taken from the Chauncey Quadrangle in the Illinois River Bluffs area,
exemplifies the information that can be expected from NWI maps.
In some areas with intense economic development and significant wetland acreage, the
NWI maps have been redone or updated for use in designating or locating wetland areas.
Whatever the source of wetland map information, the user should be aware that this
information is a general indication of wetland locations, and the boundaries and exact
locations should be field-verified by persons trained or certified in wetland delineation.
Given the limitations of most existing wetland maps, more complete information can be
obtained by comparing mapped wetlands with other regional attributes such as shallow
aquifers, subsurface geology, and placement in the landscape. When these comparisons
show consistent regional patterns (for example, placement in the landscape or correlation
with a particular geologic material), any parcels of land with similar landscape positions
or geologic materials can be considered potential wetland sites even if maps do not show
them as wet.
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boundaries for the Illinois River Bluffs assessment area. The inset area is
depicted in the following figure
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Figure 4. National Wetlands Inventory information from the Lacon 7.5-minute
quadrangle map showing wetlands, deepwater habitat, and NWI codes
Physiography
The Illinois River Bluffs area is located entirely within the physiographic division termed
the Bloomington Ridged Till Plain, as defined by Leighton et al. (1948). The
Bloomington Ridged Till Plain stretches across much of east-central Illinois, from just
west of Peoria to the Illinois-Indiana border. The topography of this region was created
primarily through the deposition of glacial till during the most recent Wisconsin Episode
of glaciation. The area is typified by extensive reaches of flat to gently rolling plains,
interrupted up by a series of end moraines, which create broad ridges of low relief. The
topography of eastern half of the Illinois River Bluffs area is most characteristic of this
physiographic division. The local relief, or change in land elevation, in this eastern half
is relatively small, with upland elevations typically in the range of 650 to 700 feet.
The western half of the Bluffs area is hilly and generally atypical of its physiographic
division. This hilly character is present primarily because the Bloomington Moraine
crosses the western half of the Bluffs region and provides additional relief to the region’s
topography. Land elevations are typically higher than those in the eastern half, with the
highest elevation in the Bluffs area, 950 feet, occurring in southern Bureau County.
The Illinois River Valley is the remnant of a much larger glacial river system that
included drainage from portions of what is now the Upper Mississippi River basin. This
larger drainage system carried significantly larger amounts of flow, including that from
glacial outwash, as was able to carve out the broad valley that the Illinois River now
occupies. Within the Illinois River Bluffs area, the width of the valley ranges from 1.5
miles at its narrowest point near Peoria to over 7 miles. The valley constriction near
Peoria occurs where the Bloomington and Shelbyville Moraines converge and cross the
river. In cutting through the upland areas of the region, the Illinois River Valley has
created significant amount of relief. The bluffs rise steeply to 150 feet above the valley
floor, which is broad and gently sloping. Tributary streams to the Illinois River have also
downcutted through the bluff line to create additional steep slopes that add relief to the
region.
Table 4 shows the distribution of land slopes for Marshall County, which spans the
Illinois River Bluffs area. Over seven percent of the land area has slopes greater than 30
percent, being located along or near the river bluffs. Over sixty percent of the land
surface is nearly level or gently sloping, and is primarily located either in the Illinois
River valley and in the upland areas in the eastern side of the county.
10
Table 4. Distribution of Land Slopes for Marshall County
Percent of land in slope category
0-2% 30.3
2-4 332
4-7 20.4
7-12 3.4
12-18 2.1
18 - 30 32
> 30 7.3
Source: Runge et al. (1969)
Land Use
Agriculture is a major land use in the eight counties (Bureau, LaSalle, Marshall, Peoria,
Putnam, Stark, Tazewell, and Woodford) in the Illinois River Bluffs area. The Illinois
Department of Agriculture, Illinois Agricultural Statistics (LAS) data indicate that in 1995
agriculture acreage accounted for approximately 31% of the total surface area in the
Illinois River Bluffs assessment area and has increased only 4% from 341,650 acres in
1925 to 370,008 acres in 1995. Figure 5 shows the changes in the harvested acres of
selected crops in the basin from 1925 to 1995.
450,000
400,000
350,000
300,000
250,000
200,000
ACRES
150,000
100,000
0
1320 1930 1940) 7 19505, 1960: W970) 1980 19,90" .2000
Figure 5. Acreages of Selected Crops in the Illinois River Bluffs Area
Based on IAS Data
In 1925 the dominant crops were grassy crops (wheat, oats, and hay) and corn, accounting
for 99% of the agricultural crops grown in the basin (170,883 acres for corn and 167,275
for grassy crops). Corn acreage has remained fairly steady over time, increasing only
slightly to levels above 250,000 acres in 1976, with a significant drop (approximately
30%) in 1983 to 167,192 acres. In 1925 soybeans were confined to little over 1000 acres;
however, it steadily increased to 167,935 acres in 1995, the most acres harvested to date.
The average grassy crop acreage from 1925 to 1950 was 140,000 and from this time
steadily decreased to approximately 13,000 acres in 1995. The inverse relationship
between soybean and grassy crop acreage is shown in figure 5, where the trends in
acreage cross during 1964-66. In 1995 the dominant crops were corn and soybeans as
opposed to corn and grassy crops in 1925. Ninety-six percent of crop acres harvested in
the Dlinois River Bluffs area is corn and soybeans (356,803 acres).
12
Climate and Trends in Climate
This chapter reviews climate trends in and around the Illinois River Bluffs area since the
turn of the century. Climate parameters examined include annual mean temperature, the
number of days with highs above or equal to 90°F, the number of days with lows below
or equal to 32°F, the number of days with lows below or equal to 0°F, annual
precipitation, the number of days with measurable precipitation, annual snowfall, and the
number of days with measurable snowfall. Extreme weather events examined in this
report are tornadoes, hail, and thunderstorms.
The Illinois River Bluffs area in north-central Illinois occupies portions of Bureau,
Putnam, La Salle, Stark, Marshall, Peoria, Woodford, and Tazewell Counties. The
climate of this area is typically continental, as shown by its changeable weather and the
wide range of temperature extremes. Summer maximum temperatures are generally in
the 80s or 90s, with lows in the 60s or 70s, while daily high temperatures in winter are
generally in the 20s or 30s, with lows in the teens or 20s. Based on the latest 30-year
average (1961-1990), the average first occurrence of 32°F in the fall is October 17, and
the average last occurrence in the spring is April 22.
Precipitation is normally heaviest during the growing season and lightest in midwinter.
Thunderstorms and associated heavy showers are the major source of growing season
precipitation, and they can produce gusty winds, hail, and tornadoes. The months with
the most snowfall are November, December, January, February, March, and April.
However, snowfalls have occurred as early as October and as late as May. Heavy
snowfalls rarely exceed 12 inches.
The climate data used in the following discussions originate at Peoria, Illinois (Peoria
County), which houses the National Weather Service (NWS) Coop site with the longest
record (1901-1996) near the southern portion of the basin. Supportive data and analyses
for nearby Illinois sites can be found in reports by the Illinois Department of Energy and
Natural Resources (1994) and Changnon (1984).
Temperature
The mean January maximum temperature is 30°F and the minimum is 13°F, whereas the
mean July maximum and minimum temperatures are 86°F and 65°F, respectively (Table
5). The mean annual temperature at Peoria is 50.7°F. The warmest year of record was
1901, with an average of 57.2°F, while the coldest was 1917, with an average of 47.8°F.
Table 5. Temperature Summary for Peoria
(Averages are from 1961-1990 and extremes are from 1901-1996. Temperatures are in °F)
#ofdays #ofdays #of days
Avg. Avg. Record Record with high =withlow — with low
i high (year) —_ low (year) >90°F $32°F
January 71 (1909) = -25 (1977) 0 28
February 34.9 17.7 74 (1932) -26 (1905) 0 25 ‘
March 48.1 29.8 87 (1907) = -11 (1943) 0 19 0.2
April 62.0 40.8 92 (1930) 14(1920) 0.1 5.8 0
May 72.8 50.9 104 (1934) 25 (1966) 1.0 0.4 0
June 82.2 60.7 105 (1934) 39 (1945) 5.6 0 0
July 85.7 65.4 113 (1936) 46(1911) 9.8 0 0
August 83.1 63.1 106 (1936) 41 (1910) V2 0 0
September 76.9 33:2 102 (1939) 24 (1942) 2.8 0.1 0
October 64.8 43.1 92 (1922) 7 (1925) 0.1 3.8 0
November 49.8 32:5 81 (1937) -2 (1977) 0 16 0.1
December 34.6 19.3 71 (1970) -24 (1924) 0 26 DD
Although there is a great deal of year-to-year variability, mean annual temperatures at
Peoria show a warming trend from 1901 to 1930, followed by a cooling trend until 1960,
warming again through 1996 (Figure 6)
56
Mean Annual Temperature (F)
- oa 164] oO oO oa oi
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nh
foe)
47
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Figure 6. Mean Annual Temperature for Peoria, 1901-1996
14
Examination of mean temperatures over time is one way to clarify trends. The NWS has
adopted 30-year averages, ending at the beginning of the latest new decade, to represent
climate "normals." These averages filter out some of the smaller scale features and yet
retain the character of the longer term trends. Consecutive, overlapping "normals" for the
last seven 30-year periods at Charleston are presented in Table 6. The consecutive means
demonstrate the warming trend through the 1931-1960 period, followed by a cooling
trend through the 1961-1990 period.
Table 6. Average Annual Temperature during Consecutive 30-Year Periods
Averaging Average
period temperature (°F)
1901-1930 51.4
1911-1940 51.8
1921-1950 51.9
1931-1960 51.9
1941-1970 51.0
1951-1980 50.5
1961-1990 50.5
The frequency of extreme events sometimes conveys a clearer picture of trends than mean
values. The annual number of days with temperatures equal to or above 90°F is shown in
Figure 7. Not too surprisingly, this bears little resemblance to annual temperature (Figure
6), because the number of days with temperatures above 90°F represents only the high
summer temperature extremes. Figure 7 shows an increase through 1938, followed by a
slow decline through 1970, before returning to somewhat higher numbers from 1971 to
1996.
= |
sol ot AY fT
SMALL TL oh
WN UW LANL
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SER Se
0
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Figure 7. Annual Number of Days with Maximum Temperatures
Equal to or Above 90°F at Peoria, 1901-1996
15
Figure 8 shows the winter frequency of daily minimum temperatures equal to or below
32°F. The frequency of such temperatures shows no trends. Figure 9 shows the number
of days per year when the minimum temperature was equal to or below O°F, beginning
with the 1903-1904 winter. No long-term trends are evident. However, there is a large
degree of variability from year to year.
160
150
=
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L_——}—j—
# of Days with Low <= 32F
80
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Figure 8. Annual Number of Days with Minimum Temperatures
Equal to or Below 32°F at Peoria, Winters 1903-1904 to 1995-1996
35
nm
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VT ATH AAA AP
PUMEAVINTVPWLA EV! VOT
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1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
# of Days with Low <= OF
Figure 9. Annual Number of Days with Minimum Temperatures
Equal to or Below O°F at Peoria, Winters 1903-1904 to 1995-1996
16
Precipitation
Mean annual precipitation at Peoria is 36.25 inches, with more rainfall in the spring and
summer than in fall and winter (Table 7). Late spring, summer, and early fall
precipitation is primarily convective in nature, often associated with short thunderstorms
(1-2 hours in duration). During the remainder of the year, precipitation is of longer
duration and associated with synoptic-scale weather systems (cold fronts, occluded fronts,
and low pressure systems).
The wettest year of record was 1990 (55.35 inches). The driest year was 1988 (22.17
inches).
Table 7. Precipitation Summary for Peoria
(Averages are from 1961-1990 and extremes are from 1901-1996. Precipitation is in inches.)
Largest one- # of
Avg. Record Record day amount Snow- days w/
Month precip. high(year) low (year) (year) fall precip.
January 15 8.11 (1965) 0.07(1919) 4.43(1965) 7.3 9
February 1.42 4.95 (1942) 0.14(1907) 2.83(1942) 5.9 8
March 2.91 6.95 (1973) 0.40(1958) 2.88(1944) 3.4 11
April CaM 8.66 (1947) 0.71(1971) 5.06 (1950) 12 12
May 3.70 11.49(1915) 0.47 (1934) 5.52(1927) 0 12
June 3.99 11.69(1974) 0.45(1936) 4.74(1911) 0 10
July 4.20 10.15 (1993) 0.33 (1988) 3.56(1953) 0 9
August 3.10 8.61 (1955) 0.25(1992) 4.32(1955) 0 9
September 3.87 13.09(1961) 0.03(1979) 4.11(1961) 0 9
October 2.65 10.53(1941) 0.03 (1964) 3.62(1969) 0.1 8
November 2.69 7.62 (1985) 0.07(1917) 4.26 (1990) 1.9 9
December 2.44 6.34 (1949) 0.29(1930) 2.52(1965) 64 9
Annual precipitation at Peoria is shown in Figure 10. No long-term trends are evident;
however, the last 10 years of data have the highest degree of variability.
The number of days per year with measurable precipitation (i.e., more than a trace) is
shown in Figure 11. No trend is evident from 1901 to 1960. From 1961 to 1996, the
variability in the number of days has increased dramatically. The much lower values in
the first few years of the record may be due to a change in exposure, location, or observer.
The annual precipitation (Figure 10) shows no such pattern, suggesting that the changes
shown in Figure 11 mainly impact the very light precipitation events. Precipitation is
more frequent during summer months than during winter months.
17
# of Days with Precipitation
Precipitation (in)
45
.=
oO
Ee)
ramen v0
I AIL EME
NN
i ae ake
Ww
oO
Ww
oO
‘i
(ia
ibe)
oa
20
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Figure 10. Annual Precipitation at Peoria, 1896-1995
ede: deo pe
A
"ti tr aa
80
70
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Figure 1]. Annual Number of Days with Measurable Precipitation
at Peoria, 1901-1996
Average winter snowfall in Peoria is 21.6 inches, with great year-to-year variability. The
most snowfall during any one winter was 52.3 inches in 1977-1978, and the least was
only 5.8 inches in 1916-1917. Figure 12 shows snowfall from winter 1903-1904 through
winter 1995-1996. A similar upward trend was evident through the mid 1980s, followed
by a slight decline through the winter of 1995-1996.
60
50
b
oO
Snowfall (in)
3
Lye]
Oo
fe caret)
TNO VA UAL
whe yen
10
e)
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Figure 12. Annual Snowfall at Peoria, Winters 1903-1904 to 1995-1996
Figure 13 shows the number of days each winter with snowfall, from 1948-1949 through
1995-1996. The number of days with snow shows a somewhat different pattern than that
for total snowfall with increases through 1966-1967, followed by decreases through 1995-
1996. A snowfall of more than 6 inches occurs about once a year. Snow cover is
frequently experienced at Peoria, lasting from a few days at a time to three months.
Precipitation Deficits and Excesses
Following are the driest years in the Illinois River Bluffs area in terms of annual
precipitation shortfall, starting with the driest: 1988, 1989, 1910, 1930, 1914, 1962,
1994, 1956, 1963, and 1901. Driest summer seasons (June, July, and August) in the basin
include: 1988, 1936, 1910, 1922, 1930, 1991, 1912, 1920, 1914, and 1933. Significantly
above average precipitation fell at Peoria in 1990, 1993, 1927, 1973, 1926, 1902, 1965,
1982, 1970, and 1985. No single decade dominated in terms of years with excessive
precipitation.
—— lah
3 25 i | Ht
2. AEE
5
0
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Figure 13. Annual Number of Days with Measurable Snowfall
at Peoria, Winters 1903-1904 to 1995-1996
Severe Weather
Tornadoes
Although tornadoes are not uncommon in []linois, most people do not expect to be
affected directly by one, even if they live in the state for a lifetime. This is because
tornadoes are generally only one-quarter mile in diameter, travel at roughly 30 miles per
hour for only 15-20 minutes, and then dissipate, affecting a total area less than 2 square
miles. Since Illinois observes an average of 28 tornadoes a year (though the actual
number varies from fewer than ten to almost 100 during the last 35 years), the total area
directly affected by tornadoes annually is only about 55 square miles, 0.1% the total area
of the state. Even with 96 tornadoes reported in Illinois in 1974 (the greatest number
reported in the last 30 years), the affected area was only about 0.3% the total area of the
state. These numbers do not diminish the effect on those experiencing property damage,
injury, or worse, but they demonstrate the extremely low probability of direct impact at
any single location.
The most recent study on tornadoes in [llinois examined events from 1955 to 1986 and
found no apparent trend in tornado frequency or intensity (Wendland and Guinan 1988).
On average, the Illinois River Bluffs area experiences about one tornado every three
years.
20
Hail
Hail events are somewhat rare and typically affect a very small area (from a single farm
field up to a few square miles). Unfortunately, very few NWS Coop sites measure hail.
The combination of small, infrequent events being measured by a sparse climate network
makes for very few reliable, long-term records of these events, particularly for large areas.
Based on Changnon (1995), the Illinois River Bluffs area experiences two hail days per
year, with the actual number varying greatly from year to year. The years with the most
hail days were 1927, 1950, and 1954, each with seven. There are no indications of trends
in hail days, based on these records.
Thunderstorms
On average, the Illinois River Bluffs area experiences about 40 days with thunderstorms
each year. The annual number of days with thunder over the Illinois River Bluffs area
since 1948 is shown in Figure 14, which is composed of data from Peoria (1948-1995).
There is substantial year-to-year variation in thunderstorm days, ranging from as many as
56 in 1975 to as few as 23 in 1968. There is no significant trend in thunderstorm days.
oa
oO
SS
oa
|
PONUNEN sooaeon cnc
IN a
ie)
ao
Saal tg eco LU
a a (a
eros are tered
1940 1950 1960 1970 1980 1990 2000
# of Days with Thunder
BS
oO
w
Oo
ie)
oO
Figure 14. Annual Number of Days with Thunderstorms
at Peoria, 1948-1995
21
Summary
Mean annual temperatures for Peoria show a warming trend through 1930, followed by a
cooling trend until the early 1960s, before warming through 1996. The number of days
with temperatures above or equal to 90°F shows an upward trend through 1938, followed
by a slow decline through 1970, before returning to somewhat higher numbers from 1971
to 1996. The number of days with temperatures below or equal to 32°F shows no trends.
The number of days with temperatures below or equal to 0°F shows no trends.
For precipitation, there are no trends. There were no trends in the number of days with
measurable precipitation. For snowfall and the number of days with snow, there was an
upward trend through the 1980s, followed by a downward trend through 1996.
Records extending back to 1901 show no clear trends in hail events. Similarly, there are
no apparent trends in tornado events, although records date only to 1955. The number of
days with thunderstorms has no significant trends since 1948.
22
Streamflow
Surface water resources are an essential component of any ecosystem because they
provide different types of habitats for aquatic and terrestrial biota. In addition to their
natural functions, they are sources of water supply for domestic, industrial, and
agricultural uses. Changes in natural and human factors, such as climate, land and water
use, and hydrologic modifications, can greatly affect the quantity, quality, and distribution
(both in space and time) of surface waters in a river basin.
There are about 1,450 miles of rivers and streams in the [linois River Bluffs area. Their
streamflow is monitored by stream gaging stations, which measure the flow of water over
time, providing information on the amount and distribution of surface water passing the
station. Since it is not feasible to monitor all streams in a basin, gaging stations are
established at select locations, and the data collected are transferred to other parts of the
watershed by applying hydrologic principles. Streamflow records are used to evaluate the
impacts of changes in climate, land use, and other factors on the water resources of a river
basin.
The streams of the Illinois River Bluffs area consist of the Illinois River and a number of
small- to medium-sized streams that drain the uplands and the bluffs. The variability of
flows on the Illinois River is to a great degree influenced by large-scale rain events and
climate influences from northeastern Illinois, which provides the major portion of the-
river’s drainage area. Many of the tributary streams in the Illinois River Bluffs area are
small, with flows rising and falling quickly in response to local climatic conditions. As a
result, it is a fairly rare coincidence for the Illinois River and the local tributaries to be
flooding at the same time or, in some cases, to be experiencing low flows at the same
time.
Stream Gaging Records
Four stream gages in the Illinois River Bluffs area, presently or previously operated by the
U.S. Geological Survey, have fifteen or more years of continuous daily flow data. These
stations are listed in Table 8 and their locations are shown in Figure 15. Also listed in
Table 8 is the Illinois River gage at Kingston Miles, located 22 miles downstream of the
Illinois River Bluffs area, which provides a longer flow record for the Hlinois River. The
Gimlet Creek gaging station is located along the bluff line, while the Crow Creek (West)
gage near Henry is located in the alluvial valley just below the bluff. The Crow Creek
gage near Washburn is located in the flatter upland portion of that stream. Stream
profiles (elevation versus distance upstream) for both Crow Creeks were given earlier
(Figure 2).
23
Cro w
xs Y
ee or
—~
S,
eh
De
5
fn andy Cre
s
é ‘ert ite
N Basin Boundary = 4 Lakes
Streams A Gaging stations
Figure 15. Stream Gaging Stations in the Illinois River Bluffs
Table 8. USGS Stream Gaging Stations with Continuous Discharge Records
Drainage Record
Area Length
. mi.) (years)
USGS ID {Station name (s Period of record
05558300 {Illinois River at Henry 13543.0 15 198 l-present
05558500 |Crow Creek (West) near Henry 56.2 22 1949-7]
05559000 |Gimlet Creek at Sparland 57 | 1950-71
05559500 |Crow Creek near Washburn 115.0 27 1945-72
05568500 |Illinois River at Kingston Mines’ 15818.0 a7 1939-present
Note: 'Located 22 miles downstream of the Illinois River Bluffs area
Human Impacts on Streamflows in the Illinois River Bluffs Area
The characteristics of streamflow in any moderately developed watershed will vary over
time because of the cumulative effect of human activities in the region. Like most
locations in Illinois, the Illinois River Bluffs area has experienced considerable land use
modification since European settlement, including cultivation, drainage modification,
removal of wetland areas, and deforestation. Most modifications began prior to the onset
of streamgaging activities, and thus their impact cannot usually be detected in the gaging
records.
Climate variability has the greatest influence on streamflows from year to year and
decade to decade. Its influence is usually large enough to help mask the impacts of the
less obtrusive human modifications to flows, including that of land use modification. The
major changes to streamflow during this century are assumed to occur from natural
climatic variability, but it is possible that in the future they may be shown to have human
influences.
Other modifications to the watershed, such as the construction of reservoirs, point
withdrawals from, and discharges to the streams have readily definable impacts on the
stream flows. The most noticeable impact of this type comes from the diversion of Lake
Michigan water to the Illinois River, for use in public water supply to most of the
Chicago metropolitan area and for maintaining water levels in the Chicago Ship and
Sanitary Canal. This diverted water accounts for over 20 percent of the total annual flow
in the river and over 70 percent of the flow during drought conditions.
ZS
Annual Streamflow Variability
Average streamflow varies greatly from year to year, and can also show sizable variation
between decades. Figures 16a and 16b show the annual series of average streamflow for
the Illinois River, and the tributaries in the Illinois River Bluffs area, respectively. For the
Illinois River, the greatest and least annual runoffs occurred in 1993 and 1964,
respectively. The long-term average flow for the Illinois River has been noticeably
greater in the last 25 years since 1970. This can be attributed to coincident increases in
annual precipitation and heavy rainfall events that have been observed in northeastern
Illinois (Knapp, 1994; Kunkel, 1997).
Streamgage records for the Illinois River at Henry indicate that the average annual flow
for 1981-1996 has been 15,680 cubic feet per second (cfs); roughly 10% greater than the
expected long-term average flow of 14,200 cfs. Of this flow amount, approximately
3,200 cfs originates from the Chicago diversion of Lake Michigan water into the Illinois
River waterway. The remaining amount of flow is runoff from all portions of the
watershed, and on average represents an equivalent runoff of 11 inches per year.
The average flow for the tributaries in the Illinois River Bluffs area do not appear to have
any trends. The average runoff of these tributaries over their periods of record ranges
from 7 to 9 inches per years, and the long-term average runoff from these streams is
expected to be about 9 inches. The greatest total annual flow on the tributaries occurred
in 1970, with an annual runoff of over 20 inches. The least annual runoff, less than inch,
was experienced in 1956.
Statistical Trend Analysis
Table 9 shows trend coefficients estimated for the annual flow record for individual
stations. The trend analysis identifies a statistically significant increase in average flow
for the Illinois River at Kingston Mines since 1939. On the other hand, the Illinois River
at Henry (1981-1996) shows a significant decreasing trend over the last 15 years. This
emphasizes the fact that trends in streamflow are dynamic and can vary significantly
depending on the period of years being analyzed.
Of additional interest is the season during which the flow increases have occurred. The
trend statistics indicate that the average streamflows during the fall season have increased
for all stations. The change in streamflows during other seasons are variable depending
on location and period of record.
26
AVERAGE STREAM FLOW, inches
AVERAGE STREAMFLOW, inches
—6— Illinois River at Kingston Mines
1940 1950 1960 1970 1980 1990
—6— Gimlet Creek at Sparland
—#-— Crow Creek near Washbum
—@— Crow Creek (West) near Henry
1945 1950 1955 1960 1965 1970
Figure 16. Average Annual Streamflow for a) the Illinois River,
and b) the Tributaries in the Illinois River Bluffs Area
27
2000
1975
Table 9. Trend Correlations for Annual and Seasonal Flows
Kendall trend correlation
Annual Fall Winter Spring
Station and Period of Record Summer
Crow Creek (West) near Henry (1949-71)
Gimlet Creek at Sparland (1950-71)
Crow Creek near Washburn (1946-72)
Illinois River at Henry (1981-95)
Illinois River at Kingston Mines (1940-95)
-0.057 0.133 0.048 -0.076 -0.152
-0.060 0.066 -0.128 0.128 -0.202
-0.303 0.121 -0.030 -0.303 0.212
0.244 0.343 0.216 0.110 0.079
Daily and Seasonal Flow Variability
Figure 17 plots the flow duration curves for the gages in the Illinois River Bluffs area.
The flow duration curve provides an estimate of the frequency with which the given flows
are exceeded. The shapes of the flow duration curves shown in Figure 17 display the
differences that would be expected between small and large watersheds. The flows for
the smaller tributaries tend to be highly variable; the peak flow rates measured at these
gages are typically five to ten times greater than the maximum flow rate averaged over a
one-day period, indicating a “flashy” nature with a quick rise and fall. Smaller streams
will also typically dry up during the late summer and fall. As shown in Figure 17, Gimlet
Creek is dry over one-third of the time. Larger streams will go dry during drought
periods, perhaps only 10 percent of the time, as shown for Crow Creek near Washburn.
The gage for Crow Creek (West) near Henry is located in an alluvial valley and shows a
more sustained amount of low flow. :
100000
10000
1000 | | —@— Crow Creek(West) near Henry
—t— Crow Creek near Washbum
—*<— Gimlet Creek at Sparland
1 —6— Illinois River at Kingston Mines
DISCHARGE, cfs
1 10 20 30 50 70 80 90 99
PERCENT CHANCE OF EXCEEDENCE
Figure 17. Flow Duration Curves (Discharge Versus Probability)
28
Flows on the Illinois River are much more gradual, influenced by the great amount of
water storage in its large watershed. The typical range of flows on the Illinois River is
from 4,000 to 50,000 cfs, with a historical minimum and maximum of 2,100 and 108,000
cfs, respectively.
As with all other locations in Illinois, streams in the Ilinois River Bluffs area display a
well-defined seasonal cycle. Figure 18 shows the probability of flow rates on Crow
Creek near Washburn for each month of the year. As shown, flows tend to be greatest
during the spring and early summer months, March through June, dropping to their
minimum values by late summer and autumn.
1000
2
Oo
wi
o
ira
<
r
re)
2
a
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 18. Monthly Flow Probabilities for Crow Creek near Washburn
Flooding and High Flows
Ramamurthy et al. (1989) and Singh and Ramamurthy (1990) examined the increases in
peak flows observed on the Illinois River for the period 1941-1985. These studies found
that the annual peak flows showed a significant increase of about 50% over this period,
and that the higher flows were caused by concurrent increases in precipitation amounts in
the river’s watershed. Northeastern Illinois, in particular, has experienced a significant
increase in the magnitude and frequency of heavy precipitation events (Kunkel et al.,
1997). The following data provide an update of these previous trend studies, using data
up through 1996, as well as information on flooding trends for tributaries in the Illinois
River Bluffs area.
29
Figure 19a shows the annual series of peak flood discharges for the Illinois River at
Kingston Mines and Henry. The two highest floods on record for the Illinois River at
Kingston Mines occurred in 1982 and 1943. As indicated by the Kingston Mines series,
there has been an gradual increase in flooding over the last 55 years; however, over the
last 15 years there has been a downward trend in peak flood values, as seen in both the
Henry and Kingston Mines records. There is no detectable trend in flooding at any of the
tributary stations, as illustrated in Figure 19b.
Statistical Trend Analysis
Results of a statistical trend analysis of flood records are given in Table 10. The results
show that the detection of flood trends is greatly impacted by the period of record being
analyzed, with higher coefficients observed when the gaging record either starts during a
drought period or ends with a major flood. Two general conclusions may be drawn from
these coefficients: 1) there is an general increase in flooding for the [linois River from
1940 to the present, but there is also a downward trend since 1981; and 2) the smaller
tributaries in the Illinois River Bluffs area have generally not experienced significant
flood trends over their period of gaging, although the flood peaks for Crow Creek near
Washburn show a reduction in flooding for the period 1946-1979.
Table 10. Trend Correlations for Flood Volume and Peak Flow
Kendall trend correlation
Station name
Crow Creek near Henry 1950-1971 0.117 o-----
1950-1976 ------ 0.014
Gimlet Creek at Sparland 1951-1971 -0.133 ------
1950-1982 —-- -0.055
Crow Creek near Washbum 1946-1972 -0.117 ------
1946-1979 ------ -0.202
Illinois River at Kingston Mines 1940-1996 0.157 0.129
1981-1996 -0.385 -0.317
Illinois River at Henry 1981-1996 -0.455 -0.250
30
DISCHARGE, cfs
1000000
DISCHARGE, cfs
100000
1945
1950 1960 1970 1980 1990 2000
—@— Crow Creek(West) near Henry
—6— Gimlet at Sparland
—f— Crow Creek near Washburn
1950 1955 1960 1965 1970 1975 1980 1985
Figure 19. Annual Peak Discharges for a) the Illinois River,
and b) the Tributaries in the Illinois River Bluffs Area
31
Impact of Peoria Lake on Peak Flows
An examination of Figure 19a also shows that, for all major flood events, the peak
discharge on the Illinois River is significantly greater at Henry than at Kingston Mines.
This occurs despite the fact that the drainage area at Kingston Mines is 20 percent greater
than that at Henry, which causes the Kingston Mines location to have a significantly
greater volume of flood waters. As illustrated in Figure 20, the peak discharges on the
Illinois River are greatly reduced when flood waters pass through Peoria Lake. The lake,
and other bottomland areas along the Illinois River, temporarily store much of the flow
volume of these major flood events. Flood water is naturally released from Peoria Lake
at a much more gradual rate, causing lower flood peaks. The outflow from Peoria Lake,
as observed at Kingston Mines, may not surpass the inflow (at Henry) for well over a
week after the peak flood flow has passed. Operation of the Peoria Lock and Dam has
minimal impact on the flood storage provided by Peoria Lake and the adjacent
bottomlands.
120000
—@ Illinois River at Henry
100000 —6- Illinois River at Kingston Mines
80000
2
o
wi
&
—< 60000
po
oO
Q
a
40000
20000
0
11/30/82 12/5/82 12/10/82 12/15/82 12/20/82 12/25/82
Figure 20. December 1982 Flood Hydrographs for the Illinois River at Henry
and Kingston Mines
Seasonal Distribution of Flood Events
Table 11 presents the monthly distribution of the top 25 flood events for four gaging
stations. For the Illinois River, major flooding occurs predominantly during spring,
March through May. For the tributaries, a combination of locally-heavy rainfall and wet
soil moisture conditions causes late spring and early summer flooding.
32
Table 11. Monthly Distribution of Top 25 Flood Events
Station Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Crow Creek (West)
near Henry 0 2 2 4 3 So 3 l 2 0 0 0
Gimlet Creek
at Sparland 0: 0 l 3 3 § 5 l l 0 0 0
Crow Creek
near Washburn
Illinois River
at Kingston Mines
Drought and Low Flows
The 7-day low flow (Q7) is used herein to describe the minimum streamflows expected
during a drought or dry period. The Q7 is defined as the minimum average flow
experienced during a seven-day period in that year. This minimum flow is useful for
evaluating the effect of dry periods on river navigation. The 7-day, 10-year low flow is
the lowest Q7 that would be expected to occur on average only once in ten years, and is
commonly used for defining the minimum amount of dilution for streams receiving
treatment effluents.
Figure 21 presents the 7-day low flows computed for the Illinois River at Kingston Mines
and the three tributary streams in the Illinois River Bluffs area. For the Illinois River,
there is a significant increase in its low flows beginning in the late 1960s. This increase
is generally proportional to and coincides with the increase in average streamflows,
presented earlier. Low flows on the Illinois River are considerably greater than they were
prior to 1900, resulting from the diversion of Lake Michigan water to the Illinois River
basin.
Many of the smaller tributaries in the Illinois River Bluffs area have zero flows during
most summers or any extended dry period. Some of the largest tributaries have at least a
small amount of flow throughout the entire year except during major droughts. The low
flow records for the tributary streams in the Illinois River Bluffs area do not show any
trends.
33
STREAMFLOW, cfs
STREAMFLOW, cfs
9000
8000
7000
6000
5000
4000
3000
2000
—@— Illinois River at Kingston Mines |
1950 1960 1970 1980 1990
—@— Crow Creek near Henry
—t— Crow Creek near Washbum
2000
Figure 21. Annual 7-Day Low Flows for a) the Illinois River,
and b) the Tributaries in the Illinois River Bluffs Area
34
1975
Summary
Since 1970 there has been a significant jump in the average annual flow in the Illinois
River Bluffs area, a trend in many Illinois rivers. This increase in streamflow directly
corresponds to a concurrent increase in average annual precipitation. There have been no
observed trends in streamflows since the early 1970s, nor were there any observed trends
in flow for the earlier period of record prior to 1970.
There has also been a general increase in high flows and low flows related to the
considerable jump in average streamflow amounts. However, the trend analysis indicates
no overall increase in peak discharges.
35
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Erosion and Sedimentation
Instream Sediment Load
Instream sediment load is the component of soil eroded in the watershed and from the
streambanks that is transported to and measured at a gaging station. It indicates the actual
amount of soil generated upstream of the gaging station and eventually transported to
downstream reaches of the river. Given the complex dynamic process of soil erosion,
sediment transport, and deposition, it is difficult to quantify how much of the soil eroded
from uplands and streambanks actually moves to downstream reaches.
The sediment transported by a stream is a relatively small percentage of the total erosion
in the watershed. However, the amount of sediment transported by a stream is the most
reliable measure of the cumulative results of soil erosion, bank erosion, and
sedimentation in the watershed upstream of a monitoring station.
There is only one gaging stations in the Illinois River Bluffs area where instream
sediment has been monitored for some time. As shown in Figure 22, this station is
located on the Illinois River at Chillicothe. Table 12 summarizes information about the
monitoring station.
Table 12. Sediment Monitoring Stations in the Illinois River Bluffs Area
USGS station Drainage area
number (sq. mi.) Period of record
05559600 Notdetermined May. 1993-Sept. 1996
Station name
Illinois River at Chillicothe
At the Illinois River near Chillicothe, the U.S. Geological Survey (USGS) monitored
sediment yield for four water years (1993-1996). Data collected by the USGS were
reported as daily average concentrations. Therefore, daily and annual sediment loads at
the station can be calculated.
Data were collected by the Illinois State Water Survey (ISWS) for two water years (1989-
1990) at ten small tributaries within the Illinois River Bluffs area, including Crow Creek,
Dry Creek, Richland Creek, Partridge Creek, Blue Creek, Funk’s Run, Tenmile Creek,
Senachwine Creek, Dickison Run, and Farm Creek. These tributaries are shown in
Figure 22, and their respective drainage areas are given in Table 13. The sediment data
collected by the ISWS were instantaneous weekly samples. Therefore, only instantaneous
sediment loads can be calculated, not average daily or annual sediment loads.
37
Scale 1:410000
0
NV Basin Boundary
Streams
A Sediment monitoring stations
Figure 22. Sediment Monitoring Stations in the Illinois River Bluffs
Table 13. Tributary Streams in the Illinois River Bluffs Area
Drainage area
Site number | Name of stream
] Crow Creek 130.0
2 and 3 Dry and Richland Creek 47.0
4 Partridge Creek 28.0
5 Blue Creek 10.5
6 Funk's Run 5.4
7, Tenmile Creek 17.6
8 Senachwine Creek 85.0
9 Dickison Run 79
10 Farm Creek 60.0
Figures 23-33 show the variabilities of daily and instantaneous streamflows (Qy),
suspended sediment concentrations (C,), and suspended sediment loads (Q,) for all
monitoring stations and tributaries. For the Illinois River at Chillicothe (Figure 23),
concentrations varied from a low of 17.7 milligram per liter (mg/1) to a high of 491.4
mg/l. Higher concentrations generally occurred in May or June for the four water years
observed.
For Crow Creek (Figure 24), concentrations varied from a low of | mg/l to a high of
4,940 mg/l over the two-year period, with higher concentrations occurring during June
and July. For Dry Creek (Figure 25), concentrations varied from a low of 6 mg/] to a high
of 13,700 mg/l. There is no significant trend in sediment concentrations for the
monitoring period. For Richland Creek (Figure 26), concentrations varied from a low of
2 mg/I to a high of 8,210 mg/] over the two-year period, with higher concentrations
occurring during May and June. For Partridge Creek (Figure 27), concentrations varied
from a low of | mg/l] to a high of 11,430 mg/l. Higher concentrations occurring during
September for water year 1989 and July for water year 1990. For Blue Creek (Figure 28),
concentrations varied from a low of 4 mg/l to a high of 22,700 mg/l. There is no
significant trend in sediment concentrations for the two-year monitoring period. For
Funk’s Run (Figure 29), concentrations varied from a low of 3 mg/l to a high of 7,120
mg/l. There is no significant trend in sediment concentrations for the two-year period.
For Tenmile Creek (Figure 30), concentrations varied from a low of | mg/l to a high of
5,690 mg/l over the two-year period. Higher concentrations occur during May for water
year 1989 and during July for water year 1990. For Senachwine Creek (Figure 31),
concentrations varied from a low of 2 mg/] to a high of 7,030 mg/l over the two-year
period, with higher concentrations occurring during June or July. For Dickison Creek
(Figure 32), concentrations varied from a low of 6 mg/l to a high of 6,950 mg/l. There is
no significant trend in sediment concentrations for the monitoring period. For Farm
Creek (Figure 33), concentrations varied from a low of | mg/I to a high of 2,870 mg/l.
Higher concentrations occurred during May for water year 1989 and during June for
water year 1990.
39
E 05559600 Illinois River at Chillicothe
10000
F
1000 =
si; * |
r ° a: o ere he
E 100E ty ele bei panies tie
>
Gj
A>) 50
: 7
21 NG le das ar ee
t ? ‘ tls Dee
a one Me Rn We % Oey Sie ae Pe : yy
me pee 3° |
a
100 ; =
10/1/92 10/1/93 10/1/94 10/1/95 10/1/96
Date
Figure 23. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for the Illinois River at Chillicothe
40
1500
Crow Creek |
.
1000
;
_~ 1000 : : :
> e
G3
<S
= 100 : one
gS :
o) Me
10 - ,
- . +4 .
] ° . al A , .
10/1/88 10/1/89 10/1/90
Date
Figure 24. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Crow Creek
4]
| Dry Creek ‘
ite
10000 E; 7 ee aT
=| 1000 by j 4 = c s : : eee
ae: : co TAR
— E e ° : *.
10/1/88 10/1/89 10/1/90
Date
Figure 25. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Dry Creek
42
300,
E Richland Creek
-
S
BI
ss E
= 100 38
g reais
= . z : .
S)
10 & ing S
F Cher =
YS I a MS a a a a de a ee er ey et Ce OY ee ee ed
10/1/90
10/1/89
Date
1
10/1/88
Figure 26. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Richland Creek
43
300 - .
¢ Partridge Creek
250
=
-
ts
200 F
SE
150 F.
. b
&
a
E
c
0
Cs (mg/l)
Qs (tons/day)
=)
oO
7 TTT Tomy Tiny =.
P 3
10 ‘
1 . i ; .
10/1/88 10/1/89 10/1/90
Date
Figure 27. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Partridge Creek
44
200 es
B
lue Creek
|
|
|
Qw (cfs) =
oO
f)
UV) UTA (aa)
S
os
=
3B
§ 100
~—
n
So
Bae : : . :
| 7 | |
10/1/88 10/1/89 10/1/90
Date
Figure 28. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Blue Creek
45
unk's Run
CF
a
nb.
E
-
Qs (tons/day)
a TTT TOT TINY
.
.
l a =
10/1/88 10/1/89 10/1/90
Date
Figure 29. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Funk’s Run
46
400
E Tenmile Creek
350 EF
l x L . | a L ; L
10/1/88 10/1/89 10/1/90
Date
Figure 30. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Tenmile Creek
47
2000
+ Senachwine Creek
mr = | :
‘ s
1000 ‘6 : Si sédsccaes 5
= . : oh -
= : en
an °
O
100000
10000
1000
Qs (tons/day)
10/1/88 10/1/89 10/1/90
Date
Figure 31. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Senachwine Creek
48
Dickison Run
Cs (me/l)
DS .
> 100 -
a2} . . °
a: | |
i= ° .
= L
oy nF : |
r ’ 3
l . ‘ . !
10/1/88 10/1/89 10/1/90
Date
Figure 32. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Dickison Run
49
T
Qs (tons/day)
= °
oO oO
T TTT T TTT
.
] ri = Os | , F “
10/1/88 10/1/89 10/1/90
Date
Figure 33. Variabilities of Flow Discharge and Instantaneous Suspended Sediment
Concentration and Load for Farm Creek
50
To provide values in tons per day, sediment load was computed by multiplying the daily
water discharge by the instantaneous sediment concentrations and applying the proper
unit conversion factors. For stations with weekly sediment sampling, it was not possible
to compute average daily and annual sediment loads. However, instantaneous sediment
load provides a range of values to compare variability of sediment from year to year and
from station to station.
For the Illinois River at Chillicothe, the sediment load varied from 284 tons per day to
93,800 tons per day for the four water years monitored. It should be noted that sediment
load depends on the size of the drainage area; therefore, a station with a larger drainage
area will generally have a higher sediment load than one with a smaller drainage area
under similar conditions.
No annual sediment load can be calculated for the Illinois River at Chillicothe. This is
because sediment load for each water year at this station was only for a period of five,
nine, or ten months (see Table 14).
Table 14. Annual Sediment Load for the Illinois River at Chillicothe
Water year Water discharge (cfs) Sediment load (tons)
1993 8,933,370 677,950 |
1994 4,836,430 730,182 7
1995 5,631,210 824,982 °
1996 4,909,800 943,638 °
Note: ' Represents a five-month total, * represents a nine-month total, and
> represents a ten-month total.
Sedimentation
Sedimentation is the process by which eroded soil is deposited in stream channels, lakes,
wetlands, and floodplains. In natural systems that have achieved dynamic equilibrium,
the rates of erosion and sedimentation are in balance over a long period of time. This
results in a stable system, at least until disruption by extreme events. However, in
ecosystems where there are significant human activities, such as farming, construction,
and hydraulic modifications, the dynamic equilibrium is disturbed, resulting in increased
rates of erosion in some areas and a corresponding increased rate of sedimentation in
other areas.
Erosion rates are measured by estimating soil loss in upland areas and measuring
streambank and bed erosion along drainageways. These measurements are generally not
very accurate and thus are estimated indirectly, most often through evaluation of sediment
transport rates based on instream sediment measurements and empirical equations.
Similarly, measurement of sedimentation rates in stream channels is very difficult and
expensive.
51
Lake sedimentation surveys provide the most reliable sedimentation measurements.
Since lakes are typically created by constructing dams across rivers, creating a stagnant or
slow-moving body of water, they trap most of the sediment that flows into them. The
continuous accumulation of eroded soils in lake beds provides a good measure of how
much soil has been eroded in the watershed upstream of the lake.
In the Illinois River Bluffs area, surveys have been conducted for 3 lakes (Table 15). The
sedimentation rates (in percent per year) for these lakes are high in comparison to most
Illinois lakes, primarily because they involve extensive watershed areas draining into
relatively small lakes.
There are no sedimentation surveys for constructed reservoirs in the Illinois River Bluffs
area. Records for the water depth of Peoria Lake have been collected and analyzed for
sedimentation rates for the years 1903, 1965, 1976, and 1985. The sedimentation analyses
for these surveys were analyzed by Demissie and Bhowmik (1986). An additional survey
by the Corps of Engineers in 1988 is not used in this analysis due to the limited record
length between the 1985 Water Survey study and the 1988 survey.
These analyses are presented in the Table 15. Comparison of the pre-1965 to the post-
1965 rates and volumes should be made with caution. The rate for the period 1903 to
1965 includes the influence of several significant alterations to the watershed and river
systems. These include 1) the early flows of the Illinois waterway from the Sanitary and
Ship Canal and the manipulation of these flows to meet court-ordered withdrawal rates
from Lake Michigan, 2) the construction of the Peoria Lock and Dam structures,
3) development of agricultural levee and drainage systems in the Illinois River Valley,
and 4) agricultural drainage systems in the Peoria Lake area that bypassed the shoreline
wetlands around the Lake.
Table 15. Lake Sedimentation Rates in the Illinois River Bluffs Area
(Volumes in acre-feet)
Year Volume Average depth Average depth loss
Lake name surveyed acre-feet feet feet per year
Upper Peoria Lake 1903 96,000 7.6
1965 55,200 4.4 0.05
1976 42,200 3.4 0.09
1985 11,800 53 0.07
Lower Peoria Lake 1903 24,000 9.8
1965 17,700 12 0.04
1976 14,400 3.9 0.12
1985 11,800 Sp) 0.07
Peoria Lake 1903 120,000 8.0
1965 72,900 4.8 0.05
1976 56,600 3.8 0.09
1985 38,300 2.6 0.13
52
Water Use and Availability
Statewide, water use has increased a modest 27% since 1965 (Illinois Department of
Energy and Natural Resources, 1994). Most of that increase is in power generation.
Water use for PWS has risen only about 7% during that time, less than the concurrent
percentage increase in population. The number of public ground-water supply facilities
in Illinois has risen significantly during that time, yet the total amount supplied by ground
water remains near 25%.
A dependable, adequate source of water is essential to meeting existing and potential
population demands and industrial uses in Illinois. Modifications to and practical
management of both surface and ground-water use have helped make Illinois’ water
resources reliable. As individual facilities experience increases in water use, innovative
alternative approaches to developing adequate water supplies must be developed, such as
use of both surface and ground waters. Major metropolitan centers such as the Chicago
area, Peoria, and Decatur, as well as smaller communities, have already developed
surface and ground-water sources to meet their development needs and to sustain growth.
The construction of impounding reservoirs has become and will remain economically and
environmentally expensive, making it a less common approach.
Proper management of water resources is necessary to ensure a reliable, high quality
supply for the population. Water conservation practices will become increasingly
important to reduce demand and to avoid exceeding available supplies. Both our ground-
water resources and surface reservoir storage must be preserved to maintain reliable
sources for future generations.
Ground-Water Resources
Ground water provides approximately one-third of Illinois’ population with drinking
water. The sources of this water can be broken down into three major units: 1) sand and
gravel, 2) shallow bedrock, and 3) deep bedrock. Most ground-water resources are
centered in the northern two-thirds of Illinois.
Sand-and-gravel aquifers are found along many of the major rivers and streams across the
state and also in “buried bedrock valley” systems created by complex glacial and
interglacial episodes of surface erosion. There are also many instances of thin sand-and-
gravel deposits in the unconsolidated materials above bedrock. These thin deposits are
used throughout Illinois to meet the water needs of small towns. Shallow bedrock units
are more commonly used in the northern third of Illinois, whereas deep bedrock units are
most widely used in the northeastern quarter (in and around the Chicago area). The
variety of uses and the volume of water used vary widely throughout the state. This
report describes ground-water availability and use in the Illinois River Bluffs area.
53
Data Sources
Private Well Information
The Illinois State Water Survey (ISWS) has maintained well construction reports since
the late 1890s. Selected information from these documents has been computerized and is
maintained in the Private Well Database. These data are easily queried and summarized
for specific needs and form the basis of well distribution studies in the area.
Public Well Information
Public Water Supply (PWS) well information has been maintained at the ISWS since the
late 1890s. Municipal well books (or files) have been created for virtually all of the
reported surface and ground-water PWS facilities in Illinois. Details from these files are
assembled in the Public-Industrial-Commercial Database, which was created to house
water well and water use information collected by the ISWS.
Ground-Water Use Information
The water use data given in this report come from the records compiled by the ISWS’
Illinois Water Inventory Program (IWIP). This program was developed to document and
facilitate planning and management of existing water resources in Illinois. Information
for the program is collected through an annual water use summary mailed directly to each
PWS facility.
Data Limitations
Several limitations must be taken into consideration when interpreting these data:
1. Information is reported by drillers and each PWS facility.
2. Data measuring devices are generally not very accurate.
3. Participation in the IWIP is voluntary.
Information assembled from well construction reports and from the IWIP is considered
“reported” information. This means that the data are as accurate as the reliability of the
individual reporting or as mechanical devices dictate. The quality of the reported
information depends upon the skill or budget of the driller or facility, respectively.
Moreover, the ISWS estimates that only one-third to one-half of the wells in the state are
on file at the Survey, mainly due to the lack of reporting regulations prior to 1976.
In general, water use measuring devices, such as the meters used by PWS facilities, are
not very accurate. In fact, errors of as much as 10% are not uncommon. Much of the
information reported in the IWIP is estimated by the water operator or by program staff.
54
Participation in the program is not required by the State of Illinois, and each facility
voluntarily reports its information through a yearly survey. However, not all facilities
know of or respond to the water use questionnaire. After several mail and telephone
attempts have been made to gather this information, estimates are made using various
techniques. To help reduce errors associated with the program, reported water use
information is checked against usage from previous years to identify any large-scale
reporting errors.
Ground-Water Availability
The Illinois River Bluffs area encompasses portions of 9 counties: Bureau, LaSalle, Lee,
Marshall, Peoria, Putnam, Stark, Tazewell, and Woodford. The portion of each county in
the watershed varies from less than 1% (Stark County) to 96% (Marshall County). This
section summarizes ground-water availability in the area, taking into consideration only
those portions of each county that are actually in the watershed.
Domestic and Farm Wells
Available regional information indicates that ground water for domestic and farm use in
the area is mostly obtained from two types of wells finished in the till (Salkregg,
Kempton, 1958). Table 16 summarizes the number of reported private wells in the
watershed by county and depth.
Table 16. Number of Reported Private Wells in the Illinois River Bluffs Area
(Source: ISWS Private Well Database)
Depth range, feet
51-100
101-150 151-200 201-250 251-300 301-350 351-400 400+
Bureau 4 4 5 12 5 4
LaSalle 10 14 12 1 3
Lee 1
Marshall 209 72) 109 33 99 27 10 3 9
Peoria 246 483 172 98 56 15 17 14 13
Putnam 90 90 66 40 44 15 1 1 5
Stark 3 4 1
Tazewell
Woodford
Public Water Supply Wells
Information from the ISWS’ Public-Industrial-Commercial Database indicates that most
ground water for PWS use in the area comes from wells finished in the unconsolidated
materials, generally the Sankoty sand, which supplies about 96% of the groundwater
withdrawn. The Cambrian-Ordovician systems supply the remaining 4%.
55
Unconsolidated wells range in depth from 23 to 408 feet, while bedrock wells range in
depth from 320 to 2,000 feet. A total of 40 public water supplies withdraw 13.50 million
gallons per day (mgd), servicing a reported 199,872 residents at an average per capita
daily water use of 71.7 gallons per day (gpd).
1995 Ground-Water Use
Ground water constitutes a substantial portion of the total water used in the basin. Total
ground-water use in the basin during 1995 is estimated to be 17.04 mgd, with 13.50 mgd
for PWS facilities, 2.14 mgd for self-supplied industries (SSI), 0.84 mgd for
rural/domestic uses, and 0.56 mgd for livestock watering.
Public Water Supply
In 1995, municipal residential use for 40 communities using ground water was reported to
be 11.70 mgd, serving a combined population of 199,872. The average per capita use
from these municipalities is 71.7 gpd. The facilities also delivered 1.80 mgd for
industrial and commercial use.
Self-Supplied Industry
Self-supplied industries are defined as those facilities that meet all or a portion of their
water needs from their own sources. In the Illinois River Bluffs area, 12 SSI facilities
reported total ground-water pumpage of 2.14 mgd during 1995.
Rural/Domestic
There is no direct method for determining rural/domestic water use in the basin. To geta
rough estimate for the area, several assumptions were made using existing information.
The population served and number of services reported by PWS facilities were used to
calculate an average population per service for all PWS facilities in the area. This
number was used as an estimate of population per reported domestic well. The average
PWS per capita use was then used as a multiplier to determine the total rural/domestic
water use from each well. Based on information from the ISWS Private Well Database,
which shows 3,646 reported wells in the Illinois River Bluffs area, an average of 3.2
people per service (well), and an average of 71.7 gpd per person, total rural/domestic
water use was estimated to be 0.84 mgd.
Livestock Watering
Water withdrawals for livestock use in 1995 were estimated to be 0.56 mgd. Water use
estimates for livestock are based on a fixed amount of water use per head for each type of
animal. Percentages of the total animal population (Illinois Department of Agriculture,
1995) for the major livestock (cattle and hogs) in the counties were calculated based upon
the percentage of county acres in the Illinois River Bluffs area. Daily consumption rates
(beef cattle = 12 gpd, all other cattle = 35 gpd, and hogs = 4 gpd) provided the basis for
these calculations.
56
Ground-Water Use Trends
Ground-water use in the Illinois River Bluffs area has remained relatively constant over
the last six years. During this period, total ground-water use has averaged 13.84 mgd and
ranged from 12.58 to 15.64 mgd; PWS use has averaged 11.85 mgd and ranged from
10.15 to 13.78 mgd; and SSI use has averaged 1.99 mgd and ranged from 1.33 to 2.55
mgd. Table 17 shows the individual totals per year since 1990. No significant trends are
evident in terms of water withdrawals in the basin.
Table 17. Ground-Water Use Trends in the Illinois River Bluffs Area
(in million gallons per day, mgd)
Surface Water Resources
The rivers, streams, and lakes of the Illinois River Bluffs area serve a wide variety of
purposes, including uses for public water supply, recreation (boating, fishing, and
swimming), and habitat for aquatic life. The primary focus of this section is on water
withdrawn from streams for public water supply and the surface water resources available
for such use.
Water supply systems generally obtain surface water in one of three manners: 1) direct
withdrawal from a stream, 2) impoundment of a stream to create a storage reservoir, and
3) creation of an off-channel (side-channel) storage reservoir into which stream water is
pumped. As described below, there is substantial potential for direct withdrawals from
the Illinois River for water supply, and several locations along the river bluffs for
potential impounding reservoirs. The potential for side-channel storage also exists along
most streams.
Water Use and Availability
The only major user of surface water for water supply in the Illinois River Bluffs area is
the city of Peoria, which withdraws water from the Illinois River. Over the six year
period, 1990-1995, the average amount of water withdrawal from the river has been 8.35
million gallons per day (mgd), or roughly 46 percent of that used for the city’s public
water supply. The only other use of surface water in the area is a small industrial supply
which reports pumping 0.03 mgd.
=f)
Most of the small communities and industries in the Illinois River Bluffs area discharge
their treated wastewater into the Illinois River. However, the total amount of these
effluents is fairly small, totaling less than 4 mgd. The city of Peoria discharges their
treated wastewater downstream of Peoria Lake. There are a few small discharges into
tributary streams, but these are not sufficient to significantly alter the flow characteristics
of such streams.
Potential for Development of Surface Water Supplies
Direct Withdrawals from Streams
The Illinois River is the only reach of stream in the area that is able to support a direct
withdrawal for water use. There are no practical limitations on the amount of water use
that could be supported by the river, and no anticipated negative impacts to its potential
use.
Impounding Reservoirs
The tributaries in the Ilinois River Bluffs area provide a number of possible reservoir
sites, primarily because of their valley slopes. Figure 34 shows the locations of 19
potential reservoir sites in the region, as given in Dawes and Terstriep (1966, 1967).
Many of the potential reservoir sites could support a safe yield in excess of 2 mgd.
In general, the construction of impounding reservoirs has become a less common option
for developing a water supply, primarily because of costs and environmental concerns.
As a result, the proximity of alternative sources should be considered in their proposed
development. Since the Illinois River provides an ample supply of water, the reservoir
sites that are farther from the river are the ones of greatest interest.
Side-Channel Reservoirs
There are no side-channel reservoirs in the Illinois River Bluffs area. The construction of
side-channel reservoirs is generally not limited by local topography and could be a viable
water supply option for a small water supply along most of the tributary streams in the
basin. The amount of water supply that off-channel storage can provide is limited
primarily by the temporal distribution of flow in the stream and the size of the storage
reservoir.
58
Dry
Richlan qd Cree,
x05.
cot
Scale 1:410000
N Basin Boundary #) Potential reservoirs
/\/ Streams
Figure 34. Potential Reservoirs in the Illinois River Bluffs
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7
aT
Ground-Water Quality
This section examines ground-water quality records to determine temporal trends and to
provide baseline water quality parameters in the Illinois River Bluffs area. Increasingly,
ground-water contamination is discussed in the news media, and it may seem that the
entire ground-water resource has been affected. However, these contamination events are
often localized and may not represent widespread degradation of the ground-water
resource. By examining the temporal trends in ground-water quality in the area, it may be
possible to determine whether large-scale degradation of the ground-water resource has
occurred.
The general term “ground-water quality” refers to the chemical composition of ground
water. Ground water originates as precipitation that filters into the ground. As the water
infiltrates the soil, it begins to change chemically due to reactions with air in the soil and
with the earth materials through which it flows. Human-induced chemical changes can
also occur. In fact, contamination of ground water is generally the result of human-
induced chemical changes and not naturally occurring processes.
As a general rule, local ground-water quality tends to remain nearly constant under
natural conditions because of long ground-water travel times. Therefore, significant
changes in ground-water quality can indicate degradation of the ground-water resource.
Data Sources
The ground-water quality data that are used in this report come from two sources: private
wells and municipal wells. The private well water quality data are compiled by the
Chemistry Division of the Illinois State Water Survey (ISWS) as part of its water testing
program and are maintained by the Office of Ground-Water Information in a water
quality database. The municipal well data come from ISWS analyses and from the
Illinois Environmental Protection Agency (IEPA) laboratories.
The combined database now contains more than 50,000 records of chemical analyses
from samples analyzed at the ISWS and IEPA laboratories. Some of these analyses date
to the early part of the century, but most are from 1970 to the present. Before 1987, most
analyses addressed inorganic compounds and physical parameters. Since then, many
organic analyses have been added to the database from the IEPA Safe Drinking Water
Act compliance monitoring program. This report presents information for only a portion
of the chemical parameters in the ISWS database.
61
Data Limitations
Several limitations must be understood before meaningful interpretation of the water
quality data can begin:
Representativeness of the sample
Location information
Data quality (checked by charge balance)
Extrapolation to larger areas
WnhN
Generally, private well samples are not representative of regional ground-water quality.
In most cases, private well owners submit samples for analysis only when they believe
there may be a problem such as high iron or an odd odor or taste. However, while one or
more constituents may not be representative, in general the remainder of the chemical
information will be accurate and useful. As a result, the composite data may be skewed
toward analyses with higher than normal concentrations.
On the other hand, private well information probably gives a better picture of the spatial
distribution of chemical ground-water quality than municipal well information because of
the larger number of samples spread over a large area. Recent IEPA data from municipal
wells will not be skewed because each well is sampled and analyzed on a regular basis.
While this produces a much more representative sample overall, samples are generally
limited to specific areas where municipalities are located. Therefore, these data may not
be good indicators of regional ground-water quality.
Much of the location information for the private wells is based solely on the location
provided by the driller at the time the well was constructed. Generally, locations are
given to the nearest 10-acre plot of land. For this discussion, that degree of resolution is
adequate. However, it is not uncommon for a given location to be in error by as much as
6 miles. To circumvent possible location errors, this report presents results on a
watershed basis.
The validity of water quality data was not checked for this report. However, previous
charge balance checking of these data was conducted for a similar statewide project
(Illinois Department of Energy and Natural Resources, 1994). Charge balance is a simple
measure of the accuracy of a water quality analysis. It measures the deviation from the
constraint of electrical neutrality of the water by comparing total cations (positively
charged ions) with total anions (negatively charged ions). Because many of the early
analyses were performed for specific chemical constituents, a complete chemical analysis
is not always available from which to calculate a charge balance.
The statewide study searched the water quality database for analyses with sufficient
chemical constituents to perform an ion balance. The charge balance checking of those
data found that more than 98% of the analyses produced acceptable mass balance, which
suggests that the chemical analyses are accurate in the database. Using that assumption
62
for this report, we feel confident that most of the analyses used are accurate and give
representative water quality parameters for the Illinois River Bluffs area. However, this
may be true only for large samples, a factor that should be considered when reviewing the
results, as this report presents data from ten decades and a wide range of sample sizes.
Extrapolating a point value (a well water sample) to a regional description of ground-
water quality is difficult theoretically and beyond the scope of this report. However, none
of the data provide a uniform spatial coverage. Therefore, it seems best to summarize the
data on a watershed basis to ensure an adequate number of values. The private well
analyses are more numerous and will likely provide better spatial coverage than the
municipal well data, which are concentrated in isolated locations.
Chemical Components Selected for Trend Analysis
In many cases, ground-water contamination involves the introduction into ground water
of industrial or agricultural chemicals such as organic solvents, heavy metals, fertilizers,
and pesticides. However, recent evidence suggests that many of these contamination
occurrences are localized and form finite plumes that extend down gradient from the
source. Much of this information is relatively recent, dating back a few decades, and
long-term records at any one site are rare.
As mentioned earlier, changes in the concentrations of naturally occurring chemical
elements such as chloride, sulfate, or nitrate also can indicate contamination. For ;
instance, increasing chloride concentrations may indicate contamination from road salt or
oil field brine, while increasing sulfate concentrations may be from acid wastes such as
metal pickling, and increasing nitrate concentrations may result from fertilizer
application, feed-lot runoff, or leaking septic tanks. These naturally occurring substances
are the major components of mineral quality in ground water and are routinely included in
ground-water quality analyses.
Fortunately, the ISWS has maintained records of routine water quality analyses of private
and commercial wells that extend as far back as the 1890s. After examination of these
records, six chemical constituents were chosen for trend analyses based on the large
number of available analyses and because they may be indicators of human-induced
degradation of ground-water quality. These components are iron (Fe), total dissolved
solids (TDS), sulfate (SOq), nitrate (NO3), chloride (Cl), and hardness (as CaCQ3).
Aquifer Unit Analysis
Ground water occurs in many types of geological materials and at various depths below
the land surface. This variability results in significant differences of natural ground-water
quality from one part of Illinois to another and from one aquifer to the next even at the
same location. For the purpose of this trend analysis, wells that were finished in
63
unconsolidated sand and gravel units were grouped together, as were wells finished in
bedrock units. Unconsolidated units are by far the most frequently used in the Illinois
River Bluffs area. Out of the more than 3,646 private wells reported in the watershed,
3,095 indicate penetration into unconsolidated units. From the water quality analyses in
the ISWS water quality database, 833 of 940 wells indicated that the water for the sample
came from the unconsolidated units. In this report, unconsolidated and bedrock aquifers
are treated separately in the descriptions of each chemical constituent.
Discussion and Results
Temporal trends in the six chemical constituents from unconsolidated and bedrock
materials are summarized in this section. Tables 18 and 19 present the results of each
decade’s analyses, including the maximum, minimum, mean, and median for each of the
six chemical constituents for unconsolidated and bedrock materials, respectively.
Median values are given in the tables by decade, beginning with 1900-1909 (Decade 0),
1910-1919 (Decade 1), and so on through the 1990s (Decade 9). Each decade covers the
corresponding ten-year period, except for the partial decade of the 1990s. Median
concentrations are given per decade so that temporal trends can be identified in the data
set. Median values are the midpoints of a set of data, above which lie half the data points
and below which is found the remaining half. These values are used to look at the central
tendency of the data set. Although the arithmetic mean would also look at this statistic, it
incorporates all data points into its analysis, which can move the mean value in one
direction or another based upon maximum or minimum values.
Outliers occur in many data sets. These are extreme values that tend to stand alone from
the central values of the data set. They may lead to a false interpretation of the data set,
whereas the median values are true values that are central to the data set. By looking at
the median we can determine trends in the central portions of the data. However, for data
sets with a small number of samples, the median may not necessarily be representative of
the water quality in the area.
It is important to recognize that the values included in these tables are reported values.
While every attempt to verify the values was made, the validity of each value with regard
to method error, etc. is not known. For this reason, the tables include every analysis in
the database and all analysis results regardless of whether a value seems excessive and
regardless of the sample size in the decade.
Table 18. Chemical Constituents Selected for Trend Analysis,
Unconsolidated Systems
Chemical constituent
Iron (Fe)
Decade
Sample size (N) 36 3 1 67
Minimum (mg/L) 0.0 0.0 0.1 0.0
Maximum (mg/L) 32 3.0 0.1 28.0
Mean (mg/L) 0.7 1.0 0.1 0.8
Median (mg/L) 0.2 0.1 0.1 0.2
TDS
Sample size (N) 39 6 1 68
Minimum (mg/l) 350.0 417.0 557.0 313.0
Maximum (mg/l) 1476.0 794.0 557.0 1964.0
Mean (mg/l) 506.5 554.2 557.0 648.5
Median (mg/1) 45505295" 1557.0) S145
Sulfate (SO)
Sample size (N) 26 4 1 67
Minimum (mg/1) 0.0 45.0 113.0 0.0
Maximum (mg/l) 38510" *110:0" “113:0"* 592:0
Mean (mg/l) 85.5 US 2" YA 1'13:09 1262
Median (mg/l) 60.5 73.0 113.0 80.0
Nitrate (NO;)
Sample size (N) 29 2 1 66
Minimum (mg/1) 0.0 1.0 31.9 0.0
Maximum (mg/1) 73.0 61.9 31.9 64.0
Mean (mg/1) 13.2 18.3 31.9 13.0
Median (mg/l) 0.0 Sel 31.9 Me]
Chloride (Cl)
Sample size (N) 40 a 1 68
Minimum (mg/1) 3.0 2.0 29.0 2.0
Maximum (mg/l) 21305) 72:0) +29:0% 7070
Mean (mg/1) 25.0 40.4 29.0 66.0
Median (mg/1) 18.0 50.0 29.0 15.5
Hardness (as CaCQ;)
Sample size (N) 36 1 1 68
Minimum (mg/l) 232.0 153.0 407.0 36.0
Maximum (mg/1) 590.0 153.0 407.0 735.0
Mean (mg/l) 379.2 153.0 407.0 423.7
Median (mg/l) 374.0 153.0 407.0 398.5
*Note: Decade 0=1900-1909, Decade 1=1910-1919,
65
169 19 55 210
0.0 0.0 0.0 0.0
16.2 4.7 8.7 14.0
1e7 0.9 1.5 1.4
0.7 0.2 0.7 0.3
188 19 49 207
306.0 366.0 308.0 248.0
1722.0 1088.0 2891.0 1179.0
517.0 562.1 590.8 475.5
452.5 464.0 454.0 449.0
179 5 8 145
0.0 57.0 0.0 0.0
559.0 447.0 235.0 370.0
70:7 "i206.850 1101.0 ¢5ie3
44.0) 45930455595 45:0
66 17 34 173
0.0 0.0 0.0 0.0
96.0 266.2 107.0 96.6
6.9 34.9 21.1 10.1
4.2 5.9 5.2 22
187 19 51 206
1.0 4.0 1.0 0.0
575.0 142.0 375.0 280.0
2TAGRE 2547 321 16.2
15.0 9.0 12.0 12.0
191 19 51 191
40 336.0 202.0 148.0
1224.0 1044.0 1810.0 650.0
379.4 462.1 414.8 358.4
352.0 404.0 342.0 348.0
and so on.
183
0.0
16.3
1.5
0.6
181
270.0
1510.0
463.2
431.0
52
125.0
1226.0
434.2
431.0
52
10.0
Table 19. Chemical Constituents Selected for Trend Analysis,
Bedrock Aquifer Systems
Decade
Chemical constituent
Iron (Fe)
Sample size (N) 3 0) 1 14 8 21 12 38 20 3
Minimum (mg/L) 0.3 0.0 0.4 0.0 0.0 0.2 0.1 0.0 0.0 0.4
Maximum (mg/L) 4.0 0.0 0.4 6.0 21.9 22.0 14.0 17.0 1.6 0.9
Mean (mg/L) 1.6 0.0 0.4 1.6 5.2 4.4 1.9 1.5 0.6 0.7
Median (mg/L) 0.4 0.0 0.4 0.3 2.4 1.2 0.8 0.6 0.5 0.7
TDS
Sample size (N) 4 1 l 14 8 24 12 37 20 3
Minimum (mg/1) 1260.0 1461.0 1454.0 356.0 374.0 1323.0 465.0 330.0 359.0 1110.0
Maximum (mg/1) 3154.0 1461.0 1454.0 3301.0 4186.0 3688.0 1510.0 6764.0 3428.0 2190.0
Mean (mg/l) 1916.0 1461.0 1454.0 1671.6 1571.2 1757.5 1049.9 1316.8 1581.0 1650.0
Median (mg/1) 1625.0 1461.0 1454.0 1446.5 1545.0 1554.5 1318.5 1306.0 1452.5 1650.0
Sulfate (SO)
Sample size (N) 4 1 1 14 i) 10 5 31 19 3
Minimum (mg/l) 107:0 <181.0.92176:005 0.0 27:0: + 110:0's5 0:0 51:0. 59:0), -208:0
Maximum (mg/1) 225.0 181.0 176.0 555.0 515.0 280.0 232.0 390.0 422.0 396.0
Mean (mg/l) 176.8 181.0 176.0 190.3 215.6 224.8 184.4 216.6 212.8 284.7
Median (mg/l) 187.5 181.0 176.0 174.0 183.0 233.0 230.0 220.0 218.0 250.0
Nitrate (NO3)
Sample size (N) 4 1 1 14 1 2 4 28 3 0
Minimum (mg/l) 0.0 0.7 1.0 0.8 0.8 0.6 0.3 0.0 0.3 0.0
Maximum (mg/l) 0.9 0.7 1.0 14.2 0.8 0.7 S16 2)k8 2.5 0.0
Mean (mg/l) 0.2 0.7 1.0 3.8 0.8 0.6 15.1 DES 1.1 0.0
Median (mg/1) 0.0 0.7 1.0 17 0.8 0.6 4.2 0.4 0.5 0.0
Chloride (Cl)
Sample size (N) 5 2 1 14 8 25 12 37 20 3
Minimum (mg/l) 360.0 580.0 458.0 2.0 9.0 420.0 1.0 3.0 12.0 200.0
Maximum (mg/l) 1725.0 725.0 458.0 1683.0 2050.0 1900.0 560.0 3750.0 1720.0 956.0
Mean (mg/l) 722.0 652.5 458.0 633.7 545.9 645.4 267.6 449.3 610.1 588.0
Median (mg/1) 485.0 652.5 458.0 505.5 382.5 540.0 300.0 450.0 534.5 608.0
Hardness (as CaCQ;)
Sample size (N) 3 0 0 14 8 25 12 32 14 3
Minimum (mg/l) 244.0 0.0 0.0 26:0 9200:0'5 42:0... 15210), 24.0. 42370 80.0
Maximum (mg/1) 430.0 0.0 0.0 1088.0 397.0 348.0 1090.0 508.0 416.0 325.0
Mean (mg/l) 321.3 0.0 0:0’ 278.1 ~285:8 223.1 ~265:2° 269:6° 25/6 1877
Median (mg/l) 290.0 0.0 0:0" "233.0, 251-5 © 220:0) 214:0) §255:0' -210'5;5 S8t0
*Note: Decade 0=1900-1909, Decade 1=1910-1919, and so on.
66
Iron (Fe)
Iron in ground water occurs naturally in the soluble (ferrous) state. However, when
exposed to air, iron becomes oxidized into the ferric state and forms fine to fluffy
reddish-brown particles that will settle to the bottom of a container if allowed to sit long
enough. The presence of iron in quantities much greater than 0.1 to 0.3 milligrams per
liter (mg/l) usually causes reddish-brown stains on porcelain fixtures and laundry. The
drinking water standards recommend a maximum limit of 0.3 mg/I iron to avoid staining
(Gibb, 1973).
Unconsolidated Systems
Iron concentrations for unconsolidated systems in the watershed are given for each
decade in Table 18. Minimum and maximum concentrations for all ten decades are 0.0
and 28.0 mg/l, respectively. These values clearly indicate a great deal of spatial
variability in iron in the watershed. The median values range from 0.1 to 0.7 mg/I for all
ten decades. While these median values show relatively high concentrations that could
cause staining of porcelain fixtures (greater than 0.3 mg/l), they generally pose no threat
to human health. In addition, the median values are all well above the Class I potable
ground-water supply standard of 0.5 mg/l. Table 18 suggests no significant trend in iron
concentrations in the area.
Bedrock Aquifer Systems
Iron concentrations for bedrock aquifer systems in the watershed are given for each
decade in Table 19. Minimum and maximum concentrations for all ten decades are 0.0
and 22.0 mg/l, respectively. These values clearly indicate a great deal of spatial
variability in iron in the watershed. The median values range from 0.3 to 2.4 mg/I for all
ten decades. While these median values show relatively high concentrations that could
cause staining of porcelain fixtures (greater than 0.3 mg/l), they generally pose no threat
to human health. Table 19 suggests no significant trend in iron concentrations in the area.
Total Dissolved Solids (TDS)
The TDS content of ground water is a measure of the mineral solutes in the water. Water
with a high mineral content may taste salty or brackish depending on the types of
minerals in solution and their concentrations. In general, water containing more than 500
mg/l] TDS will taste slightly mineralized. However, the general public can become
accustomed to the taste of water with concentrations of up to 2,000 mg/]. Water
containing more than 3,000 mg/l TDS generally is not acceptable for domestic use, and at
5,000 to 6,000 mg/I, livestock should not drink the water. Because TDS concentration is
a lumped measure of the total amount of dissolved chemical constituents in the water, it
will not be a sensitive indicator of trace-level contamination. However, it is a good
indicator of major inputs of ions or cations to ground water.
67
Unconsolidated Systems
TDS concentrations in the unconsolidated systems in the watershed are given for each
decade in Table 18. Minimum and maximum concentrations for all ten decades are 125.0
and 2,891.0 mg/l, respectively. Median values range from 431.0 to 557.0 mg/I for all ten
decades. Generally, there are no significant trends in TDS concentrations in these
aquifer systems in the watershed.
Bedrock Aquifer Systems
TDS concentrations for bedrock aquifer systems in the watershed are reported for each
decade in Table 19. Minimum and maximum concentrations for all ten decades are
330.0 and 6,764.0 mg/l, respectively. Median values range from 1,306.0 to 1,650.0 mg/]
for all ten decades. Generally, there are no significant trends in TDS concentrations in
bedrock aquifer systems in the watershed. Any fluctuations from one decade to the next
are more likely related to data limitations than to any inherent changes in ground-water
quality.
Sulfate (SO4)
Water with high sulfate concentrations often has a medicinal taste and a pronounced
laxative effect on those not accustomed to it. Sulfates generally are present in aquifer
systems in one of three forms: magnesium sulfate (sometimes called Epsom salt), sodium
sulfate (Glauber’s salt), or calcium sulfate (gypsum). They also occur in earth materials
in a soluble form that is the source for natural concentrations of this compound. Human
sources similar to those for chloride also can contribute locally to sulfate concentrations.
Coal mining operations particularly are a common source of sulfate pollution, as are
industrial wastes. Drinking water standards recommend an upper limit of 250 mg/I for
sulfates. Upward trends in sulfate concentrations can suggest potential ground-water
pollution.
Unconsolidated Systems
Sulfate concentrations for unconsolidated systems in the watershed are reported for each
decade in Table 18. Minimum and maximum concentrations for all ten decades are 0.0
and 868.0 mg/l, respectively. Median values are all well below the drinking water
standard, and range from 37.0 to 113.0 mg/I for all ten decades. Fluctuations from one
decade to the next are more likely related to data limitations than to any inherent changes
in ground-water quality.
Bedrock Aquifer Systems
Sulfate concentrations for bedrock aquifer systems in the watershed are reported for each
decade in Table 19. Minimum and maximum concentrations for all ten decades are 0.0
and 555.0 mg/l, respectively. Median values are all well below the drinking water
standard, and range from 174.0 to 250.0 mg/l for all ten decades. Table 19 indicates
variability, but no significant trends in sulfate concentrations in the watershed.
Fluctuations from one decade to the next are more likely related to data limitations than
to any inherent changes in ground-water quality.
68
Nitrate (NO3)
Nitrates are considered harmful to fetuses and children under the age of one when
concentrations in drinking water supplies exceed 45 mg/l (as NOs), or the approximate
equivalent of 10 mg/I nitrogen (N). Excessive nitrate concentrations in water may cause
“blue baby” syndrome (methmoglobinemia) when such water is used in the preparation of
infant feeding formulas. Inorganic nitrogen fertilizer has proven to be a source of nitrate
pollution in some shallow aquifers, and may become an even more significant source in
the future as ever increasing quantities are applied to Illinois farmlands. Upward trends
in concentrations of nitrate may be a good indication that farm practices in the area are
affecting the ground-water environment.
Unconsolidated Systems
Nitrate concentrations for unconsolidated systems in the watershed are reported for each
decade in Table 18. Minimum and maximum concentrations for all ten decades are 0.0
and 266.2 mg/l, respectively. Maximum concentrations should be viewed as an outlier of
the dataset, and not as representative of the water quality in the area. The majority of the
median values are well below the drinking water standards, and range from 0.0 to 31.9
mg/l] for all ten decades. However, the ISWS has documented numerous cases of
elevated nitrate levels associated with rural private wells in and around this area (Wilson
et al., 1992). The evidence suggests that rural well contamination is associated more with
farmstead contamination of the local ground water or well than with regional
contamination of major portions of an aquifer from land application of fertilizers. This
topic is actively being studied.
Bedrock Aquifer Systems
Nitrate concentrations for bedrock aquifer systems in the watershed are reported for each
decade in Table 19. Minimum and maximum concentrations for all ten decades are 0.0
and 51.6 mg/l, respectively. Median values are well below the drinking water standards,
and range from 0.0 to 4.2 mg/l for all ten decades.
Chloride (Cl)
Chloride is generally present in aquifer systems as sodium chloride or calcium chloride.
Concentrations greater than about 250 mg/l usually cause the water to taste salty.
Chloride occurs in earth materials in a soluble form that is the source for normal
concentrations of this mineral in water. Of the constituents examined in this report,
chloride is one of the most likely to indicate the impacts of anthropogenic activity on
ground water. Upward trends in chloride concentrations may indicate contamination
from road salt or oil field brine. The drinking water standards recommend an upper limit
of 250 mg/l for chloride. In sand and gravel aquifers throughout most of the state,
chloride concentrations are usually less than 10 mg/l.
69
Unconsolidated Systems
Chloride concentrations for unconsolidated systems in the watershed are reported for each
decade in Table 18. Minimum and maximum concentrations for all ten decades are 0.0
and 707.0 mg/l, respectively. Median values are well below the drinking water standard,
and range from 9.0 to 50.0 mg/l for all ten decades. Table 18 indicates no significant
trends in chloride concentrations in the watershed.
Bedrock Aquifer Systems
Chloride concentrations for bedrock aquifer systems in the watershed are reported for
each decade in Table 19. Minimum and maximum concentrations for all ten decades are
1.0 and 3,750.0 mg/l, respectively. Median yalues range from 300.0 to 652.5 mg/l for all
ten decades. Table 19 indicates no significant trends in median chloride concentrations in
the watershed. Fluctuations from one decade to the next are more likely related to data
limitations than to any inherent changes in ground-water quality.
Hardness (as CaCQ3)
Hardness in water is caused by calcium and magnesium. These hardness-forming
minerals generally are of major importance to users since they affect the consumption of
soap and soap products and produce scale in water heaters, pipes, and other parts of the
water system. The drinking water standards do not recommend an upper limit for
hardness. The distinction between hard and soft water is relative, depending on the type
of water a person is accustomed to. The ISWS categorizes water from 0 to 75 mg/l as
soft, 75 to 125 mg/1 as fairly soft, 125 to 250 mg/I] as moderately hard, 250 to 400 mg/l as
hard, and over 400 mg/l as very hard.
Unconsolidated Systems
Hardness concentrations for unconsolidated systems in the watershed are reported for
each decade in Table 18. Minimum and maximum concentrations for all ten decades are
4.0 and 1.810.0 mg/l, respectively. Median values range from 153.0 to 407.0 mg/I for all
ten decades, indicating moderately hard to hard water in this area.
Bedrock Aquifer Systems
Hardness concentrations for bedrock aquifer systems in the watershed are reported for
each decade in Table 19. Minimum and maximum concentrations for all ten decades are
23.0 and 1,090.0 mg/l, respectively. Median values range from 158.0 to 290.0 mg/I for
all ten decades. The water is considered moderately hard in this area. No trends are
observed in hardness concentrations from the bedrock in this area.
70
Summary
This work was undertaken to examine long-term temporal trends in ground-water quality
in the Ilinois River Bluffs area. Data from private and municipal wells were the primary
sources of information used to show the trends in six chemical constituents of ground
water in the area. These data demonstrate that on a watershed scale, ground water has not
been degraded with respect to the six chemicals examined. Fluctuations from one decade
to the next are more likely related to data limitations than to any inherent changes in
ground-water quality. It is also evident that the sample size in each decade can play a role
in trend analysis.
Much of the contamination of Illinois’ ground water is localized. Nonetheless, this
contamination can render a private or municipal ground-water supply unusable. Once
contaminated, ground water is very difficult and expensive to clean, and clean-up may
take many years to complete. Clearly it is in the best interests of the people of Illinois to
protect their ground-water resource through prevention of contamination.
Although no significant trends in water quality for these six constituents are apparent, the
information provides baseline water quality for the watershed. This information can be
used in future studies of the area as a reference to determine whether the local ground-
water quality is degrading.
71
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References
Introduction
Illinois Department of Natural Resources. 1996. Illinois Land Cover, An Atlas. IDNR-
96/05. Springfield, IL.
Illinois Department of Natural Resources. 1996. Illinois Land Cover, An Atlas. Compact
Disc. Springfield, IL.
Leighton, M.M., G.E. Ekblaw, and L. Horberg. 1948. Physiographic Divisions of
Illinois. Dlinois State Geological Survey Report of Investigation 129. Champaign, IL.
Mattingly, R.L., and E.E. Herricks. 1991. Channelization of Streams and Rivers in
Illinois: Procedural Review and Selected Case Studies. Illinois Department of
Natural Resources Report ILENR/RE-WR-91/01.
Suloway, L., and M. Hubbell. 1994. Wetland Resources of Illinois: An Analysis and
Atlas. Illinois Natural History Survey Special Publication 15. Champaign, IL.
Climate and Trends in Climate
Changnon, S.A., Jr. 1984. Climate Fluctuations in Illinois: 1901-1980. Illinois State
Water Survey Bulletin 68. Champaign, IL.
Changnon, S.A., Jr. 1995. Temporal Fluctuations of Hail in Dlinois. [linois State Water
Survey Miscellaneous Publication 167. Champaign, IL.
Illinois Department of Energy and Natural Resources. 1994. The Changing Illinois
Environment: Critical Trends. Volume 1: Air Resources. ILENR/RE-EA-94/05(1).
Springfield, IL.
Streamflow
Knapp, H.V. 1994. Hydrologic Trends in the Upper Mississippi River Basin. Water
International 19 (4): 199-206.
Kunkel, K.E., K. Andsager, and D.R. Easterling. 1997. Trends in Heavy Precipitation
Events over the Continental U.S. Manuscript.
Ramamurthy, G.S., K.P. Singh, and M.L. Terstriep. 1989. Increased Duration of High
Flows along the Illinois and Mississippi Rivers: Trends and Agricultural Impacts.
Illinois State Water Survey Contract Report 478.
Erosion and Sedimentation
Demissie, M., L. Keefer, R. Xia. 1992. Erosion and Sedimentation in the Illinois River
Basin. ILENR/RE-WR-92/04, Springfield, IL.
73
Water Use and Availability
Dawes, J.H., and M.L. Terstriep. 1966. Potential Surface Water Resources of North-
Central Illinois. Illinois State Water Survey Report of Investigation 56.
Dawes, J.H., and M.L. Terstriep. 1967. Potential Surface Water Resources of North-
Central Hlinois. Hlinois State Water Survey Report of Investigation 58.
Illinois Department of Energy and Natural Resources. 1994. The Changing Illinois
Environment: Critical Trends. Volume 2: Water Resources. ILENR/RE-EA-
94/05(2). Springfield, IL.
Selkregg, L.F., and Kempton, J.P., 1958. Groundwater Geology in East-Central Illinois,
Illinois State Geological Survey Circular 248.
Ground-Water Quality
Gibb, J.P. 1973. Water Quality and Treatment of Domestic Groundwater Supplies.
Illinois State Water Survey Circular 118. Champaign, IL.
Illinois Department of Energy and Natural Resources. 1994. The Changing Illinois
Environment: Critical Trends. Volume 2: Water Resources ILENR/RE-EA-
94/05(2). Springfield, IL.
Wilson, S.D., K.J. Hlinka, J.M. Shafer, J.R. Karny, and K.A. Panczak. 1992.
“Agricultural chemical contamination of shallow-bored and dug wells.” In Research
on Agricultural Chemicals in Illinois Groundwater: Status and Future Directions II.
Proceedings of the second annual conference, Ilinois Groundwater Consortium,
Southern Illinois University, Carbondale, IL.
74
(EE ——————————
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