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Atlas of
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Resources
Section I
Water Kesources
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Climate
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UNIVERSITY OF ILLINOIS LIBRARY
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Atlas of
Illinois
Resources
Section I
Water Kesources
and
Climate
STATE OF ILLINOIS
BOARD OF
ECONOMIC DEVELOPMENT
Governor Otto Kerner,
Chairman
Victor deGrazia.
Executive Director
Printed by Authority of
the State of Illinois
November. 1958
CONTENTS
Water Resources of Illinois
Water Resources of Illinois 1
Runoff and Stream Flow 4
Seasonal Variations in the Hydrologic Cycle 4
Mean Annual Runoff and Seasonal Variations in the Hydrologic Cycle 5
Minimum Runoff 6
Minimum Runoff, 6, 12, 18, 24-Month Periods 7
Developed Surface Water Supplies and Potential Development 8
Surface Water 9
Sedimentation 10
Reservoir Sedimentation Surveys 11
Ground Water Geology 12
Bedrock Geology 13
Sand and Gravel Aquifers 14
Sand and Gravel Aquifers and Recorded Pumpage 15
Limestone Aquifers 16
Limestone Aquifers and Recorded Pumpage 17
Sandstone Aquifers 18
Sandstone Aquifers and Recorded Pumpage 19
Industrial Water Pumpage 20
Industrial Water Pumpage 21
Irrigation 22
Irrigation Systems 23
Mineral Quality of Illinois Waters 24
Municipal Water Softening Plants 25
Mineral Quality of Illinois Waters (continued) 26
„...^.. Ground Water Hardness and Iron Content and Municipal Treatment 27
t
AvERAGE Annual and Monthly Precipitation 28
Average Annual Precipitation 29
Frequency of Annual Maximum and Minimum Precipitation 30
Lowest and Highest Annual Precipitation Expected Once in 5 and 50 years .... 31
Long-Period Precipitation 32
Long-Period Record oj Annual Precipitation: St. Louis, Peoria, Chicago,
and Cairo 33
Snowfall 34
Average Annual Snowfall 35
Heavy Snowfall and Deep Snow Cover 36
Occurrence of Icing Conditions 36
Average Annual Days with Snow/all of 1 Inch or More and Average Annual
Icing Conditions 37
Thunderstorms, Hail, and Tornadoes 38
Average Annual Thunderstorms and Hail and Tornado Occurrences 39
Temperatures 40
Mean January and July Temperatures 41
Heating and Cooling Degree Days 42
Average Annual Heating and Cooling Degree Days 43
Growing Season 44
Average Length of Growing Season 45
Illinois Water Rights Law 46
Major State Agencies Dealing with Water Supplies 49
Selected Reference List of Documents Pertaining to Water Resources 50
Glossary 52
Index of Counties, Cities, and Towns 54
Urban Population and Location 59
Research Agency
Illinois State Water Survey Division
William C. Ackermann, Chief
H. F. Smith, Coordinator
Glenn E. Stout
Stanley Changnon, Jr.
T. E. Larson
Gustavo Patino
W.J. Roberts
John B. Stall
Further Research Contributors
Robert E. Bergstrom
Illinois State Geological Survey Division
John E. Cribbet
College of Law, University of Illinois
John L. Page
Department of Geography, University of Illinois
Produced by
Department of Geography, University of Illinois
Joseph A. Russell, Head
Fred W. Foster, Directing Consultant and Editor
James A. Bier, Cartographer
Gilbert H. Topp, Draftsman
Produced for
Division of Industrial Planning and Development, State of Illinois
WATER RESOURCES OF ILLINOIS
Illinois is a water excess state, which means this resource is available in excess of
demand. In fact, the water available to the state is conservatively computed to be at
least five times the present usage.
Illinois is almost an island, in a sense being surrounded by fresh water. Along
its western border flows the mighty Mississippi and to the south and east are the
Ohio and Wabash. Lake Michigan lies to the northeast. This is far from all, for larger
supplies are readily available within the state in the form of great rivers such as the
Rock, the Illinois, and the Kaskaskia, as well as many smaller streams. Out of sight,
but important as sources of water supply, are the ground waters in the soil and in the
deep rock formations.
Illinois' water resources are as large today as when this area was a wilderness,
and so far as modern science can determine, they will be undiminished and constantly
renewed by a great inflow of atmospheric moisture or water vapor in the air which
averages 2000 billion gallons (bgd) per day. From this source of moisture the rather
ineflScient processes of nature cause only about 5 percent to fall as rain or snow, yet
this mere 5 jjercent averages 99 bgd for the state. Evaporation from land and water
surfaces and the transpiration from growing plants have first call on this water;
together they consume and return to the atmosphere about 76 bgd. Some 23 bgd of
stream flow, including ground water, are available from within the state, which, when
added to the minimum flow of record on the Mississippi and Ohio, as well as the
present pumpage and diversion from Lake Michigan, brings the grand total mean
daily surface and ground water supplies available to Illinois to 43 bgd. This is an im-
mense amount of water — five times the present state usage and one-sixth of the water
usage for all purposes in the entire United States.
Of course, water is not uniformly available either in place, in time, or in quality.
Variations of the water resource are in part due to the great north-south dimension
of Illinois, since within this 385 miles of latitude there is variation with respect to
storm tracks and in distance from the primary moisture source in the Gulf of Mexico.
For these and other reasons, precipitation varies from about 46 inches per year in the
Shawnee Hills of southern Illinois to 32 inches in the vicinity of Lake Michigan. Most
of this larger precipitation in southern Illinois occurs in the winter season, and about
5 percent of this falls as snow. In northern Illinois about 20 p>ercent of the winter pre-
cipitation is snowfall.
Runoflf in the form of stream flow varies arcally in much the same pattern as pre-
cipitation, and if spread over the state would vary in depth from about 16 inches per
year in the south to 8 inches in the north. The higher runoff" in southern Illinois in
conjunction with more rolling or hilly land surface lends itself well to the develop-
ment of surface water impoundments. Northern Illinois, on the other hand, is more
HYDROLOGIC CYCLE
fortunate in the generally available ground water in unconsolidated glacial material
and in the deep rock formations.
As is well known, rainfall and stream flow also vary in time. To an extent these
variations are cyclic with the seasons of the year, but wide deviations from the aver-
age trend are more the rule than the exception. In addition to the seasonal and day-
to-day changes there are the occasional extended periods of excess or drought. The
years 1952-1955 constituted such a period of extended drought, not only in Illinois
but throughout much of the mid-continent. Once experienced, an extreme period of
record such as this becomes an important guide to future engineering planning and
design. This drought of 1952-1955 has been the subject of intensive study and it
is estimated to have been of a severity which can be expected only once in about 80
years.
Water also varies widely in quality, and this has been and still is the subject of
intensive study in Illinois through the analysis and correlation of thousands of water
samples each year. Water does not exist in the chemically pure form of H2O, but
contains dissolved and suspended material from both natural and man-made sources.
Also, there is no universally ideal water quality for all purposes. Illinois waters are
usually mineralized to a degree, are moderately hard, and may contain iron and
various other substances. Two points are important in this regard: information on
water quality is available; and chemical, physical, and bacteriological treatment
methods are available to adjust any original element of natural water quality within
desirable limits.
Complete knowledge for the full and economic development of water resources
requires far more than data on rainfall and stream flow. Even the list of closely re-
lated physical factors is long. These include topographic and geologic maps for the
location of dam sites, and rates of evaporation and sedimentation for the design of
reservoirs. Water temperature data are of great importance since the largest single use
for water in Illinois is for cooling purposes in industrial processes. Air temperature
and wet bulb data are needed in the design of air conditioning equipment, another
important use for water.
Present and projected uses for water in Illinois are factors of importance in our
water resources knowledge and are subjects of continuing study. Present use of water
in Illinois by major user categories is approximately 6 bgd for thermal power stations,
2 bgd for all other industrial applications, 1.4 bgd for municipal use, and smaller
amounts for agricultural uses. These growing uses, which presently total some 9.5
bgd, compare with a potential, useful resource of about 43 bgd.
Much of the foregoing discussion on water availability, its character, and its
present usage underlines the necessity for detailed water resources information ex-
tending over many years and in adequate detail. In this regard Illinois is indeed
fortunate, since its water resources have been under increasingly intense study since
the creation of the State Water Survey in 1895. This agency, working with the State
Geological Survey and other state agencies, has accumulated a wealth of information
on the water resources of the state. It has been said that Illinois has better records on
its water resources than any comparable area in the world, and this knowledge is vital
to the effective development and utilization of the water and other natural resources
of the state.
The pages which follow contain a brief but factual summary of water resources,
climate, and related data. Through reference to available documents given in the
reference list or to the indicated state agencies dealing with water supplies, more de-
tailed information can be obtained. The right to use water is contained in a discus-
sion of Illinois water rights law.
RUNOFF AND STREAM FLOW
W. J. Roberts
Natural surface flow of water is termed runoff. In Illinois, 23 billion gallons of
the approxiinately 100 billion gallons of average daily precipitation eventually run
off in streams. The performance of these streams is determined from the study of long
periods of stream flow records; the State Water Survey and other agencies cooperate
with the U.S. Geological Survey in obtaining continuous records at 161 stream gag-
ing stations within or along the borders of the state.
Stream flow is usually expressed in cubic feet per second. This value is some-
times converted to cubic feet per second per square mile of drainage area, or to
inches of runoflf. Inches of runoff represents the depth to which a drainage area would
be covered if all the flow derived from it during a period of time were distributed uni-
formly on its surface. This latter term is useful when comparing runoff with pre-
cipitation.
The map shows the distribution of mean annual runoff in Illinois as obtained
by using the average data for 25 stations. Drainage basins for these stations reach into
Wisconsin in two instances and into Indiana in one. A considerable variation in
runoflf occurs within the state; it ranges from less than 8 inches in the west and north-
east to more than 16 inches in the hill area of southern Illinois.
SEASONAL VARIATIONS IN THE HYDROLOGIC CYCLE
W. J. Roberts
Precipitation continues in motion when it reaches the earth's surface. Its course
depends upon the degree to which it is afl'ected by the processes of infiltration, evapo-
ration, transpiration, percolation, underground travel and detention, and surface flow.
The influences and natural interrelationships of these processes vary with the seasons.
Their effects may be studied best by beginning with the quantitative data available
for rainfall and runoff and then from this base calculating the eflfects of the less well
measured processes of evaporation and transpiration. The illustration opposite is the
graphical result of such a procedure.
It demonstrates that water passes into storage during the spring and fall periods
when the evaporation and transpiration rates are low. It shows how the rainfall de-
ficiency of the warm months results in a lowering of ground water levels and a reduc-
tion in soil moisture. During drought years the recovery of ground water levels and the
resumption of normal stream flow from such deficiencies may be seriously delayed.
MEAN ANNUAL RUNOFF
20 to 40 -Year Records
for 25 Stations
Illinois State Water Survey
Irkcties per Yeor
I I «-'
Trantpiration p
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Roir
tall minuiRunotf
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SEASONAL VARIATIONS
IN THE HYDROLOGIC CYCLE
Southern Illinois
Illinois State Water Survey
I Slot* Wol«f Sur«*v
Jan. Feb. Mor. Apr. May June July Aug. Sept. Oct. Nov. Dec.
MINIMUM RUNOFF
W. J. Roberts
Minimum runoff is measured in terms of minimum stream flow, and is usually ex-
pressed in cubic feet per second at a specified location for the drainage area of the
stream involved. Results may be stated in inches for comparison with rainfall data.
The value in inches is determined by calculating the depth to which an area would
be covered if the stream flow for a given period were uniformly distributed over its
drainage basin. The minimum runoff record will reveal the least amount of water
available during periods of low runoff and consequently will indicate the storage
capacity necessary for water storage facilities to meet the demands during such periods
of low runoff.
Observations from stream-gaging stations are of limited use for design purposes
until they have been collected for at least 20 years. Data may then be tabulated by
months, for instance, and totals for various periods calculated. The lowest value for
the entire period of record can then be determined and plotted on a watershed map.
In order to map minimum runoff, data are entered in the center of each drainage
area. Isolines are so drawn that each runoff value represents the mean of its watershed
area.
At the end of the 1952-1955 drought, a study applicable to central and southern
Illinois revealed that this period had the lowest runoff of record. Maps were drawn of
minimum runoff for periods of from six months to five years duration. They showed
that runoff was less than 5 percent of normal for 20,000 square miles in southern
Illinois during a one-year period and less than 25 percent of normal for approximately
the same area during a two year period. Thus, many water supply reservoirs, already
overtaxed by increased municipal and industrial demands, were virtually emptied by
the balance of out-flow over in-flow during the drought years.
The designers of new water supply reservoirs require a knowledge of all water-
shed characteristics, including the size and shape of the drainage area, the soil types
present, and slope relationships. A consideration of the values expressed by the mini-
mum runoff map is also important in reaching proper design decisions.
MINIMUM RUNOFF
Lowest Q-Month Period on
Record, August. 1953, to
July, 1954, Inclusive
^i^?imMi<^
MINIMUM RUNOFF
Lowest 6-Month Period
on Record, August, 1953,
to January, 1954, _/
Inclusive '^ \
Illinois Slate Water Survey
MINIMUM RUNOFF
Lowest 18-Month Period
on Record, August h^-^
to December, 1954
Inclusive
DEVELOPED SURf#:E WATER SUPPLIES
AND POTENTIAL DEVELOPMENT
W. J. Koberts
There are over 900 water bodies in Illinois which merit being classed as lakes or
reservoirs; in addition there are thousands of farm ponds. They may be either natural
or artificial, and range through lakes, impounding reservoirs, and sloughs. Natural
lakes are associated with parts of the glaciated area in the very northern part of the
state, particularly Lake County; these waters are used principally for recreation.
Fortunately, ground water is available locally in amounts sufficient to meet the needs
of municipal water systems and no cities or towns rely on surface water for their public
supplies in this northern part of the state.
The greatest use of the state's surface water is from rivers — the Mississippi, the
Wabash, the Ohio— with the addition of the considerable supplies obtained from
Lake Michigan. Rivers within the confines of the state, such as the Rock, the Illinois,
the Kaskaskia, the Embarrass, and the Big Muddy, also make sizeable contributions
of water.
There are large reservoirs in central Illinois, such as Lake Springfield, Lake
Bloomington, Lake Vermillion, and Lake Decatur, designed for surface water storage.
These are primarily water supply reservoirs but they also provide opportunities for
recreation. Population and industrial growth in the cities served by these facilities is
increasing demands on the supplies to such an extent that the need for expanded
storage capacities already is apparent. Centers such as Mattoon and Effingham, hard
hit by the drought of the early 1950's, have already taken steps to improve their situa-
tions by building new reservoirs.
Nearly all the larger communities in the southern third of the state rely on im-
pounding reservoirs for their municipal water supplies. Having outgrown their
original facilities, many have built new reservoirs since World War II. Crab Orchard
Lake, the state's largest impounding reservoir, covers 11 square miles and has a
storage capacity of 67,320 acre-feet. Including other tributory reservoirs, completed
or in the final stages of development, the total facility will eventually be able to pro-
vide for a continuous draft of approximately 50 million gallons a day.
A recent study of the potential water resources of the 17 southern Illinois counties
presents a favorable picture for the future. Hydrologic data indicate that reservoir
sites are available for the potential development of a storage capacity able to supply
700 million gallons of water daily.
Surface waters are present in abundance in Illinois. There are many good sites
awaiting development. Storage facilities for recreational, municipal, and industrial
use are constantly in development and it can be said with assurance that the physical
potential exists for a vast water resource development in this state.
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SURFACE WATER
Illinois Stole Water Survey
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GROUND WATER GEOLOGY
Robert E. Bergstrom
Ground water in Illinois is usually obtained from deposits of sand and gravel
in the glacial drift or from the limestone or sandstone formations of the underlying
layered bedrock. In both cases, the occurrence of favorable supplies depends upon
several factors, some relating to the source and physical character of the water itself
and others to the requirements of the user.
The availability of ground water is controlled mainly by the presence of earth
materials that store and transmit water. These materials, called aquifers, vary greatly
in water-yielding capacity and are distributed in uneven fashion throughout the
state. Other earth materials such as silt, clay, and shale may contain abundant water
in the minute pores between grains but they retard movement of the water to such an
extent that it cannot flow freely into a well.
Aquifers are replenished (recharged) by water that seeps directly into the ground
from precipitation or from streams or lakes. The rate of recharge of an aquifer often
determines whether ground water withdrawal can be maintained safely for a long
period of time.
The mineral and bacterial quality of the water itself aflfects the availability of
favorable supplies. In general, ground water is more highly mineralized at greater
depths. The result is that some aquifers yield potable water only where they are close
to the land surface.
In addition to natural factors, the requirements of the user affect the suitability
of an area for ground water development. For example, where large supplies are re-
quired, as for an industry, or where water of specific chemical quality or temperature
is needed, only certain areas of the state may be considered favorable.
The map on the facing page shows the distribution and water-yielding character-
istics of the various bedrock formations below the glacial drift; the cross sections il-
lustrate the vertical arrangement of the formations, including the glacial drift.
Bedrock formations (Cambrian through Devonian) are favorable aquifers in the
northern third of Illinois where potable supplies are obtained to depths of 1 500 feet or
more. However, these formations dip southward to a much greater depth in south-
central Illinois, where a troughlike structure, the Illinois Basin, is developed (cross
section AA'). Here they contain salt water.
The Mississippian, Devonian, and Silurian limestones, which are aquifers of
small yield west of the Illinois River and at the southern tip of the state, also dip
toward the Illinois Basin. Here they are overlain by Pennsylvanian rocks — mainly
shale — in which only small scattered supplies of ground water are available. Most of
the area covered by Pennsylvanian rocks is relatively unfavorable for obtaining
ground water from the bedrock.
12
ILLINOIS RtVER
BEDROCK
GEOLOGY
Generalized
Illinois Stote Geological Survey
BEDDOCK
[ j TERTIARY ond CRETACEOUS:
cm
I I MISSISSIPPIAN:
I I DEVONIAN ond SILURIAN: Wol«i
I I ORDOVIOAN: Wolor-yi.ldinj d<
W Dei Ploinei foulled complen
SAND AND GRAVEL AQUIFERS
Robert E. Bergstrom and H. F. Smith
Most of Illinois is mantled by unconsolidated deposits left by the glaciers that
overrode the north-central United States during the "Ice Age." The greatest southern
penetration of the ice in Illinois was about to Carbondale. The last great glacial ad-
vance in the state reached as far south as Shelbyville and Mattoon and as far west as
the Mississippi River north of Rock Island.
Glacial ice sheets, moving outward from centers of snow accumulation in
Canada, scraped up soil and rock debris, transported it southward, and eventually
dropped it along the melting ice borders. Deposits related to glacial times are mainly
of three types, as they exist today: till, outwash, and loess. Till is a mixture of un-
sorted, silty, sandy, pebbly clay deposited directly from the ice. Sands, gravels, and
silts spread by the meltwaters are termed outwash. Loess occurs on uplands as de-
posits of wind-blown silt from the river flats.
Outwash sands and gravels are one of the main sources of ground water in
Illinois. Outwash was deposited mainly in valleys leading away from the ice fronts.
Thus the valley systems that were in existence before and during glaciation are today
excellent water-producing areas. In these sand and gravel-filled areas large quanti-
ties of water are available from relatively shallow wells that are usually drilled to less
than 300 feet. Some of the valley systems are occupied by streams today, among them
the valleys of the Mississippi River, the Wabash River, the lower two-thirds of the
Illinois River, and the Kaskaskia River. In these instances coarse deposits of outwash
occur beneath recent river alluvium.
Other valleys were completely buried or obliterated by glacial deposits and are
known today only from drilling records. The Mahomet Valley of east-central Illinois
is one of the most important and best known. The thick sand and gravel beds in this
buried valley provide ground water for many municipal and industrial supplies.
The upland areas between the valleys were not flooded with meltwater carrying
outwash. Sand and gravel deposits are therefore less extensive and ground water con-
ditions are accordingly less favorable.
Because northeastern Illinois was covered by glaciers during several stages of the
"Ice Age," the deposits here are thicker and more varied than in southern and west-
ern parts of the state where only the earlier glacial deposits are present. In most of the
northeast, moderate quantities of ground water can be secured from sand and gravel
aquifers in the glacial drift. In the western and southern parts of the state, where the
drift is thin and composed mainly of till and loess, little water can be secured from the
drift except in the flood plains of the major streams.
SAND AND GRAVEL
AQUIFERS AND
RECORDED PUMPAGE
Illinois State Geological Survey
Illinois State Water Survey
LIMESTONE AQUIFERS
Robert E. Bergstrom and H. F. Smith
Wells in limestone and dolomite, the latter a limestonelike rock rich in mag-
nesium, draw water mainly from openings in the rock— joints, fissure systems pro-
duced by earth stresses, and channels opened and enlarged by water solution. These
rocks are commonly too dense to yield much water from pore spaces as do sandstone
and other granular deposits. Because the water-filled fissure systems are irregular in
size and distribution, yields from closely spaced, similarly constructed wells in lime-
stone and dolomite may be quite different.
Particular attention to sanitary conditions is necessary in planning wells in a
limestone or dolomite area. When either is the uppermost bedrock formation, whether
exposed at the surface or overlain by thin glacial drift, there is danger of bacterial
pollution entering the ground water reservoir. Quarries may be sources of such con-
tamination. The openings provide little filtering or other purifying action, and pol-
luted water may travel long distances.
The Silurian dolomite, commonly called Silurian limestone, is a source of ground
water in northeastern and northwestern Illinois as shown on the facing map. Many
municipal and most domestic wells in Du Page County and southern Cook County
are drilled into these rocks. These wells are usually less than 500 feet deep and yield
from a few gallons to over 1000 gallons per minute.
Ordovician dolomites and limestones, specifically the Galena-Platteville beds,
are widely used as a water source in that part of northern Illinois where they occur
directly below the glacial drift. Under these conditions they provide dependable,
although only small-to-moderate, supplies. However, where they are overlain by the
uppermost Ordovician shale formation (Maquoketa) they are usually poorly fissured
and yield little ground water.
Mississippian limestones (St. Louis and Keokuk-Burlington) are a source of
ground water chiefly west of the Illinois River. Usually the yields are not more than
10 to 20 gallons per minute. Wells in these formations are used mainly for domestic
supplies. South and east of the Illinois River, water-yielding limestones containing
potable water are generally absent, except in two small areas. In Douglas and Cham-
paign Counties water-yielding Devonian and Silurian limestones occur below the
glacial drift along the crest of a north-south arch in the bedrock. At the southern tip
of the state, limestone wells are constructed in Mississippian, Devonian, and Silurian
limestones along the south rim of the Illinois Basin. These wells range in capacity from
less than 20 gallons to over 500 gallons per minute.
LIMESTONE AQUIFERS
AND RECORDED
PUMPAGE
Illinois Stole Geological Survey
Illinois Stole Water Survey
MISSISSIPPIAN
DEVONIAN ond SILURIAN
[MTTH ORDOVICIAN
Recorded Pumpage in
Gallons per Minute per Well
cm HO
I I 20 to 100
h^'»- I 100 to 500
o
J Ov.r 500
o
SANDSTONE AQUIFERS
Robert E. Bergstrom and H. F. Smith
Ground water is obtained from sandstone in many parts of Illinois. The most
favorable area is the northern fourth of the state, where large supplies are available
from the thick, extensive Galesville and Mt. Simon sandstones of Cambrian age
and the St. Peter sandstone of Ordovician age.
The Cambrian and Ordovician sandstone aquifers, which are separated by about
400 feet of less permeable beds, are near the surface in south-central Wisconsin and
north-central Illinois. From these localities they dip southeastward and wells may
be drilled to 2000 feet in tapping these rocks in the vicinity of Chicago. The Gales-
ville sandstone is the most consistently permeable of the three aquifers and supplies
water for high-capacity wells producing 300 to 1500 gallons per minute.
The Cambrian and Ordovician sandstone aquifers are under artesian pressure —
that is, water rises in a well above the top of the producing aquifer. Artesian con-
ditions are a result of the aquifers being overlain by "tighter" beds which hold the
water under pressure maintained by the head developed at the higher intake areas
to the west and north. Many of the early wells drilled into the sandstones flowed at the
surface; however, the artesian pressures receded as more and more high capacity
wells were drilled. Today, water levels are over 500 feet below ground surface in a
few places in northeastern Illinois.
The water from the sandstones is highly mineralized east of the Des Plaines
River and south of the Illinois River. The line A-A' on the map is approximately
the southern limit of potable water (less than 1 500 parts per million total dissolved
solids) in these sandstones. For lack of more suitable water supplies, wells are drilled
locally to the sandstones a short distance south of this line (to B-B') .
In the central and southern parts of the state thin sandstone beds in the Penn-
sylvanian system yield small quantities of water, seldom more than 10 gallons per
minute. Also, there are a few areas where Mississippian sandstones yield ground water
along the southwestern border of the state. Wells in these sandstones have low capaci-
ties, rarely exceeding 20 gallons per minute.
18
SANDSTONE AQUIFERS
AND RECORDED
PUMPAGE
Illinois State Geological Survey
Illinois Slate Woler Survey
INDUSTRIAL WATER PUMPAGE
w . J. ixuL'f I i:
Industrial pumpage refers to water pumped by industry from private sources.
There is some industrial pumpage in nearly every county in Illinois. However, 10
industrial centers — Chicago, Joliet, the Fox Valley, La Salle, Rockford, Sterling,
Rock Island, Peoria, Decatur, and East St. Louis — dominate the situation from the
standpoint of volume. There are a few smaller areas where pumpage amounts to
between 5 and 10 million gallons per day. Individual industries scattered within the
state account for 90 million gallons of daily production.
A total of approximately 1700 million gallons per day is pumped by 489 estab-
lishments, either from their own wells or from private surface water sources. Of this
total over 250 million gallons per day are pumped by 394 industries from ground
water, while 95 establishments pump over 1450 million gallons of surface water daily.
In addition to the private pumpage, industry buys approximately 350 million
gallons of water per day from municipalities. If water used by hydroelectric gener-
ating plants and steam generating electric plants is included, industry in Illinois re-
quires more than eight billion gallons in day-to-day operations.
Large as this total seems, it is very small compared to the amount of water avail-
able from the streams, rivers, and ground water supplies of Illinois. The quantities
of water needed for an increasing population and for industrial growth and expansion
are present in amounts sufficient to meet all foreseeable future needs.
3 1
20 30 40 50 60
70
„„„„„.;,„„„„„
90 1
Precipitation 99 Billion Gallons i
1 i 1 1 ^
n
Power 6 Billion Gallons
1
Industrial 2 Billion Gallons
1
Municipal 1.4 Billion Gallons
Agriculture 0.13 Billion Gallons
(half in irrigation)
AVERAGE DAILY PRECIPITATION AND PUMPAGE
20
Illinois
INDUSTRIAL
WATER PUMPAGE
Not Including Municipal Water
Supplied to Industry
Illinois State Water Survey
IRRIGATION
W. J. Roberts
Supplemental irrigation has been practiced in Illinois for about 30 years. From
a few systems operated in Kankakee County in 1925, the practice has spread to
76 Illinois counties where in 1957 an estimated 338 separate systems could water
approximately 16,500 acres. The accompanying distribution map of irrigation systems
in Illinois shows the greatest concentration in Kankakee County. Here over 50 gladiola
growers supplement rainfall with sprinkler systems that use water from wells. There
are also isolated systems depending on wells in several other counties, including Cook,
Lake, and Woodford. Many developments are located in the alluvial plains of the
principal rivers; others make use of ponds, lakes, and streams. In Madison County
18 wells have been put into operation in recent years to supply additional moisture
for the high- value horse-radish crops.
Adequate water supply is the principal locational factor in irrigation. Topography,
soil type, crop to be grown, and the availability of labor are also important con-
siderations. Many irrigation systems have been purchased for use in Illinois without
thought for the large amount of water necessary for efficient operation. With the
advent of light, portable pipe about 1950, many farmers invested heavily only to
find that their water sources were dry at times of critical need. In recent years nearly
all irrigation systems have been purchased only after thorough studies of water avail-
ability. In Illinois, the State Water Survey and the State Geological Survey have
data available on the quality and quantity of surface water and ground water for
any part of the state. The University of Illinois College of Agriculture has prepared
sprinkler system guides for surface irrigation. The Department of Agricultural En-
gineering at the University has several circulars on irrigation available for distribu-
tion and also conducts irrigation clinics for salesmen, engineers, and interested farmers.
At present, the greatest returns from investment appear to be from growing
high income crops. Normally the rainfall during the growing season plus water
stored in the soil is adequate for soybeans and corn. Thus a considerable increase
in crop output would be necessary to justify an investment in irrigation equipment
for the major field crops.
Present Illinois laws do not define the rights of land owners regarding use of
water for irrigation. Local shortages and the ensuing competition for water have
created difficulties in some cases. The prospective user of irrigation equipment in
Illinois should, therefore, assess the availability of water sufficient for his purpose,
the cost of supply, and the competitive aspects of the situation before selection of any
specific location.
22
T'
IRRIGATION SYSTEMS V^ h-^" 1
Illinois State Woter Survey (f"
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MINERAL QUALITY OF ILLINOIS WATERS
T. E. Larson
In the natural course of events, water is virtually an indestructible chemical
compound. Although it exists in many forms and places, its availability in the free
state — as atmospheric, surface, or ground water — is the primary concern of man.
Beyond the universal necessity of water for survival, man's interests are directed
toward having the right quality in the right amount at the right time. One aspect
of fundamental interest, especially in our industrialized world, is the chemical con-
tent of water. Any discussion of this subject revolves around surface and ground
water supplies, as the amounts of chemicals in atmospheric moisture are so small
they are seldom significant.
Water comes close to being the universal solvent; certainly this is the case in
its natural role. In its movement over and within the earth's surface, water dissolves
or otherwise collects mineral and organic substances. The nature of this burden
varies with time and place, and there is, from man's standpoint, no combination
of substances that will suit every use. For today's mechanized society, the presence
of dissolved or suspended substances may affect the utility' of water. In the past,
industries often were located with respect to water of suitable quality. The great
demands placed upon the resource largely preclude this possibility today, but methods
now available can be used to modify or remove the dissolved and suspended com-
ponents in water to the extent that any water can be made suitable for almost any
purpose. Costs, however, may exceed the economic benefit, so the public and in-
dustry alike are alert to this problem as new sources of water are developed and
old sources expanded.
Water in Illinois is usually mineralized to a degree, is hard, and may also con-
tain either some form of iron or suspended matter. The qualities of the available
supplies are such, however, that these substances can be successfully and economically
removed if they prove undesirable. Surface and well waters of the state are similar
in hardness and other mineral content. There are, naturally, significant exceptions.
All public water supplies obtained from streams, lakes, and reservoirs are clarified
and chlorinated as a basic treatment, supplemented with treatment for taste and
odor control, and are frequently softened.
In general, streams in the northern part of the state have an average dissolved
mineral content of about 450 parts per million (ppm) and a hardness of about 400
ppm. Values decrease to near 300 ppm mineral content and 250 ppm hardness in
western and southern Illinois. The waters from Crab Orchard Lake in the extreme
south are exceptionally low in mineral content and hardness, running 200 ppm and
110 ppm respectively.
Fifty-four of 288 municipalities of over 2000 population, drawing water from
streams and wells, have installed water softening plants. In addition, the public
24
MUNICIPAL WATER
SOFTENING PLANTS
Illinois State Water Survey
_.-L-L.V
V'l BLOOMINGTON I J
I 1 y 1 Rantuul '
^ I • Villa On
^J^ DECATUR J J ^1^ r^
^ (Jacksonville \ J \ I i [ ^
j SPRINGFIELD
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On« wolef M>ft«ning plant
L
water supplies of 80 smaller communities receive softening treatment. Lake Michigan
water, which supplies 57 communities in addition to Chicago, is noted separately, as
its mineral content is uniformly at 150 ppm and its hardness 125 ppm. Large scale
softening is not indicated.
In Illinois, approximately 35 percent of the public ground water supplies have
less than 0.4 ppm iron concentration, which is not sufficient to cause staining. In
addition, 27 percent of the systems containing more than this amount have iron
removal plants. All clarified surface water supplies are free of iron. Manganese is
present in sufficient quantities to stain in about 5 percent of the public ground water
supplies, and about one-half of these communities remove it by treatment.
Stream temperatures, as a general rule, vary from 32° to 75° or 85° F. between
winter and summer. Ground water on the other hand, shows no great temperature
variations and those that occur are gradual changes associated with depth beneath
the surface of the earth. Water from depths less than 300 feet in the northern part of the
state varies from 48° to 54° F. With greater depths this value often increases and
may rise as high as 62° or 64° F. at between 1600 and 2000 feet. In the south, water
from depths of less than 300 feet may be between 55° and 60° F. West of the Illinois
River and south of Rock Island, deep well waters from 1400 to 2400 feet may have
temperatures as high as 72° to 76° F.
Water is abundant in Illinois today, and is sufficient to serve a growing popula-
tion and an expanding industry. It is also very important to know that these supplies
are suited chemically and temperaturewise for most public and private uses. When
this is not the case the qualities are such that water treatment is economically feasible.
Perhaps a greater problem concerning our water supply is contamination by man.
The waste materials he may add to water can be much more difficult to remove than
nature's mineral and organic substances.
36
Ground Water
WATER HARDNESS AND
MUNICIPAL SOFTENING
Wotar Mftened by
r-
-n
;
r-
777
^
■
JZ ^
ZTXi
^
2Z:
i
^
100 200 300 400 500 600 700 800
Total Hordness (in ports per miltion)
Illinois State Water Survey
Number of Public
Ground Water Supplit
-
'uuuuA
^^
Y////////i
Ground Water
IRON CONTENT AND
MUNICIPAL REMOVAL
Total Iron (in ports per million)
AVERAGE ANNUAL AND MONTHLY PRECIPITATION
Stanley Changnon, Jr.
Precipitation in Illinois varies considerably in time and space. The annual
average amount is lowest in northeastern Illinois near Lake Michigan, where it is
less than 32 inches. The highest average annual precipitation, more than 46 inches,
occurs in the hill region of southern Illinois. The precipitation which produces this
annual excess of south over north occurs during the colder half-year (October through
March). For the warmer half-year (April through September), the average precipita-
tion varies only from 20 inches in the north to 24 inches in the south, while during
the six colder months the precipitation varies from 12 inches in northern Illinois to
23 inches in southern Illinois.
Precipitation in Illinois is associated principally with the interaction of different
air masses within the state. The nature of the continental type of climate allows fre-
quent penetrations throughout the year of different types of air masses and their
associated weather disturbances. These often produce rain or snow. The basic dif-
ference between winter and summer precipitation is related to the character of the
air masses. Relatively cold, dry air masses predominate in the winter, especially
in the north, while relatively warm, moist air masses predominate in the summer.
During the warmer months, the chmate throughout the state is much the same. This
similarity in basic warm season conditions is in part expressed by the lack of a real
variability in the average precipitation of the warmer half-year. Fifty-four percent of
the annual precipitation in southern Illinois occurs during the crop-growing season,
61 percent occurs during this period in central Illinois, and 64 percent in northern
Illinois.
During the colder half-year a striking north-south difference in climate exists.
Although the southern Illinois winter is much colder than the summer, the tempera-
tures are warm enough and the air sufficiently moist to produce thunderstorms
and summer- type characteristics in the winter precipitation. However, in central and
northern Illinois the predominating cold, dry continental air does not permit the
development of heavy precipitation.
The average annual number of days with measurable precipitation increases
from west to east across the state from an average of 110 days per year in the west
to an average of 120 days in the east. However, the average annual number of days
with 0.25 of an inch or more increases from 38 in northern Illinois to 50 in the south.
February is the month of lowest average monthly precipitation throughout most of
the state. There is, however, a latitudinal distribution from south to north in the
average maximum monthly rainfall. March and April are peak months in southern
Illinois. May predominates in central Illinois and June has the highest average in
the north.
28
Average Annual
PRECIPITATION
With Average Monthly Amounts
at Selected Locations
llinois State Water Survey
FREQUENCY OF ANNUAL MAXIMUM
AND MINIMUM PRECIPITATION
Stanley Changnon, Jr.
Due to the great variability in annual precipitation from year to year, the annual
averages are not representative of the conditions that can be expected to occur in
any particular year. To express this variability, the occurrence of the annual maximum
and minimum precipitation amounts expected on an average of once in 5 and once
in 50 years are shown on the accompanying maps. For example, the annual minimum
precipitation may be 22 inches or lower once in 50 years in northeastern Illinois;
in the same period, a single year low of 28 to 30 inches can be expected in southern
Illinois. Likewise, the highest annual precipitation expected once in 50 years in
southern Illinois is 74 or more inches, while the probable maximum is 44 inches or
more in the extreme northeastern part of Illinois for the same span of time.
Since 1950, "once in 50 years" extremes of precipitation have occurred in Il-
linois. For instance, in 1957 Cairo received 72.98 inches, which was the wettest year
in 86 years of record, and this was the second total since 1900 to exceed the 69.21
inches expected to be equalled or exceeded once in 50 years, on the average, at this
station. Similarly, Paris, with 63.90 inches in 1957, exceeded the "once in 50 years"
expected amount of 51.28 inches for the first time in 57 years of record.
Recent years have also provided precipitation totals that equaled or exceeded
"once in 50 years" extremes of minimum precipitation. During the 1952-1955 drought
in the southern half of Illinois several locations experienced extremely dry years. For
instance, Mount Vernon had 27.50 inches in 1953. This was the second year since
1901 with a total below 27.64 inches, the "once in 50 years" expected low at the
station.
Prolonged drought periods lasting one year or longer occur infrequently in
Illinois and seldom affect the entire state. Furthermore, most droughts or rainfall
deficiency periods which may occur can not seriously affect surface water supply
sources if proper reservoir design is employed.
30
LOWEST ANNUAL
PRECIPITATION
EXPECTED
Once in 5 Years
Illinois State Woter Surve
HIGHEST ANNUAL
PRECIPITATION
EXPECTED
Once in 5 Years
LONG'PERIOD PRECIPITATION
John L. Kagc
In the selection of weather stations to portray long-period precipitation in Illinois,
the length of the available record, the continuity of the record, and the degree to
which these represent various parts of the state were of primary concern. Cairo and
Chicago would seem to raise no questions in meeting the above qualities. There is
no station in Illinois which has precipitation records approaching the length and
continuity of those from St. Louis, Missouri. This station can well represent the
southwestern part of the state. Peoria has the only long and continuous record for
the area north and west of Springfield.
Neither for Illinois as a whole nor for any individual station is there a definite
precipitation cycle over a period of years. Periods of varying length with relatively
low, as well as relatively high, precipitation exist, but there is no periodicity. From
1872 — the year for which all four stations first reported — through 1957 there have
been 18 years when all stations had precipitation above the average. Only on one
occasion did all four have precipitation above the average for as many as three con-
secutive years: 1882, 1883, and 1884. Only on three other occasions did all stations
have precipitation above the average for even two consecutive years.
During 19 different years all stations had precipitation below the average, but
only on one occasion was it below for as many as three consecutive years: 1899, 1900,
and 1901. In 1955 and 1956 the precipitation was below average at all stations for
the only other occasion with as many as two consecutive years. Cairo and Peoria
have each had five consecutive years with precipitation above the average, while
Chicago and St. Louis have each had six. Chicago's precipitation has been below
average for no more than three consecutive years, Peoria for four, St. Louis for five,
and Cairo for seven. For the four stations as a whole 1930 was driest, though this
was not the driest year for any one of them, and 1957 the wettest, but actually the
wettest only for Cairo.
If there has been any permanent change in the amount of precipitation over
the years, these four stations do not reveal it. If the record for each station is divided
into quarters, certain facts appear. At Cairo the driest quarter of the record averages
38.71 inches, the wettest 45.89 inches, while at Peoria the driest quarter averages
34.84 inches and the wettest 34.96 inches, for the greatest and least departures. The
percentage departure from normal for the driest and wettest year has been 63 and
173 at Cairo, 60 and 180 at St. Louis, 66 and 153 at Peoria, and 67 and 139 at Chicago.
The variation from year to year and the absence of any pattern for the state as a
whole, or for individual stations, makes long-period forecasting on the basis of trends
impossible as of now. However, if past records in any way reflect the future, it may
be assumed that precipitation will continue to supply Illinois with water equal to
the amount of the past.
32
Long-Period Record of
ANNUAL PRECIPITATION
St. Louis, Peoria, Chicago,
and Cairo
Peorio 34.90 il
Chitooo 33.01 ir
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10
SNOWFALL
Stanley Changnon, Jr.
The distribution of snowfall in Illinois is directly related to the normal north-
south differences in the winter temperatures. Under conditions which bring on
precipitation during the colder half-year, moisture which falls as snow in northern
Illinois usually falls as rain in the southern part of the state. Northwestern Illinois
is the area of maximum snowfall, receiving over 36 inches annually. This is nearly
four times more than that normally falling in the extreme south. The location of this
area of greatest snowfall is associated with cold, polar continental air which normally
predominates northwest of Illinois during the winter season. Moderating temperatures
related to differences in latitude are responsible for the decreasing average annual
snowfall as one progresses southward. Local conditions and influences, of course,
give rise to some irregularities in this pattern.
January is the month of highest average snowfall in the north and in a small
area in the extreme south. However, February is the peak month for the area bounded
on the north by a line from Alton to Danville and on the south by an east-west line
crossing the state not far north of Cairo. Northern Illinois stations show measurable
amounts of snow for seven months of the year on the average, as compared to only
four months on the average in the south.
Record Maximum Snowfai
Jan. Feb. Mar.
Rockford 36.1 21.8 23.5
Urbana 18.2 18.5 32.0
Cairo 24.2 11.7 11.7
Jan. Feb. Mar.
Rockford T T T
Urbana T T
Cairo
Apr.
May June
July Aug.
Sept.
Oct.
Nov.
Dec.
Annual
9.0
1.5 T
T
5.0
14.8
26.5
62.1
8.0
2.5
2.5
11.2
18.0
39.9
1.6
1.5 T
2.0
6.1
22.7
47.7
Reco
RD Minimum Snowfall
Apr.
May June
July Aug.
Sept.
Oct.
Nov.
Dec.
Annual
T
8.8
T
6.7
0.4
T = Trace
34
Illinois
Induifriol Planning and D*»el
Average Annual
SNOWFALL
With Average Monthly Amounts
at Selected Locations
MOLINE
AVERAGE SNOWFALL
In Inches
j
34.38
1
3034
1
24-30
1
22-24
1
18-22
14-16
10-14
8-10
HEAVY SNOWFALL AND DEEP SNOW COVER
The average annual number of days with snowfalls of 1 inch or more varies
from three in southern Illinois to thirteen in the northwestern part of the state. This
northward increase is gradual throughout the southern half of Illinois, with Quincy
and Urbana averaging only three more days per year than Cairo. However, north
of a line from Quincy through Urbana — which is, incidentally, near the mean winter
isotherm of 32° F. — the number of days increases quite rapidly. An average of nine
days per year is reached at both Moline and Chicago.
The occurrence of heavy snowstorms — those yielding 4 inches or more snowfall
in less than 48 hours — also reveals the same south-to-north increase. In southern Illinois
a snowfall of this magnitude can be expected once a year. In central Illinois such
snowstorms occur from one to two times a year, while in the north the average oc-
currences are between two and three a year.
The number of days with 1 inch or more of snow on the ground also has a dis-
tribution closely related to the north-south temperature pattern. On the average,
over fifty days a year in northern Illinois have 1 inch or more of snow cover while
only ten days a year have 1 inch or more of cover in southern Illinois.
OCCURRENCE OF ICING CONDITIONS
The distribution of the average annual number of days with icing conditions
of sleet and glaze reveals an area of maximum occurrence in central Illinois. Glaze
conditions occur in .areas with temperatures at or near 32° F., during precipitation
periods. The latitudinal distribution of temperatures during the winter is such that
near freezing circumstances prevail with greater frequency in central Illinois than
elsewhere in the state. The winter temperatures in southern Illinois are generally
too warm to result in many glaze conditions, while the temperatures in northern
Illinois are generally too cold.
The average annual occurrences of sleet vary only slightly from place to place
in Illinois, with station averages ranging between five and seven days per year. Most
of the variation in icing conditions relates to the glaze or freezing rain component,
with areas of maximum development in central Illinois and near Lake Michigan.
Average Annual
Number of Days with
SNOWFALL OF I INCH OR MORE
And with Ground Snow Cover of
Inch or More and 3 Inches or More
at Selected Locations
age Number of Days
1
13-U
1213
11.12
10-11
1
9-10
8-9
1
7-8
4-7
5-4
4-5
3-4
Stote Water Survey
THUNDERSTORMS, HAIL, AND TORNADOES
The average annual frequency of thunderstorms in the Middle West decreases
northward from the Gulf of Mexico. Storm activity in Illinois generally reflects this
decrease with changing distance from the Gulf; there is an average annual occurrence
of 58 thunderstorms in Cairo compared with 37 at Chicago. However, in western
Illinois there is a northward increase in thunderstorms, as shown on the accompany-
ing map, appearing primarily as an increase in the frequency of nocturnal thunder-
storms, principally in August and September. June is the month of maximum thunder-
storm occurrence throughout the state and January is the month when they are least
in evidence.
Thunderstorms are a large contributor to the total precipitation of the state.
The percent of the normal annual precipitation derived from this source increases
from 38 percent in northeastern Illinois to over 44 percent in the south and to above
50 percent in the western section of the state. Thunderstorms make their greatest
contribution to normal monthly rainfall during July, when 70 to 85 percent of the
total is produced in this manner. Annual average thunderstorm precipitation is lowest
in the northeast, where less than 13 inches fall, and highest in the south, where it
measures over 19 inches.
The average annual occurrences of hail in Illinois have a varied distribution,
with areas of maximum frequency in the unglaciated hill region of the northwest,
the hill region of the south, and the Springfield Plain area in the southwest. These
areas are identified in terms of surface features, since hail occurrences are considered
to be related to conditions of topography. Hail occurrences vary considerably from
year to year throughout the state. May, with an average of eight days, is the month
of maximum activity. April, averaging six days, and March, averaging five days,
rank second and third highest. Hail activity on a single day is more likely to be wide-
spread during March and April than in other months.
The distribution of tornado occurrences for the 25-year period of 1927-1952
shows great areal variation. Some small areas in southern Illinois had as many as
nine and other areas in southeastern and northeastern Illinois experienced as few
as one for this period. One belt of maximum activity extends from the southwestern
peak area northeastward through the Champaign-Danville area, and another such area
extends northwestward towards Moline. Over 70 percent of all tornadoes in Illinois
occur during a four-month period, March-June, and March is the month of maximum
tornado activity.
Average Annual
THUNDERSTORMS
with Average Monthly Occurrences
at Selected Locations
I ■ ■-■•■i 36-40
^■1 56-«0
c:^
Average Annual
HAIL OCCURRENCES
Average Number
TORNADO OCCURRENCES
FOR 25 YEARS
1927-1952
Averoge Number
of Occurrences
E33<
Sw4
7or8
Illinois State VVoter Survey
TEMPERATURES
Stanley Changnon, Jr.
The continental climate of Illinois can be expected to exhibit extreme variations
in temperature from day to day, month to month, and year to year. These variations
will be considerably less, hov^ever, in the warmer half of the year than in the colder
six-month period. While occasional spells of severe cold are a characteristic of southern
Illinois winters, the climate during this season is basically milder here than in the rest
of the state. Summers are commonly warm- to-hot and usually humid throughout
Illinois. The annual mean temperature in northern Illinois is 48° F.; it is 60° F. in the
south. An annual mean variation of 12 degrees exists, therefore, between these ex-
tremes of the state.
In July, the warmest month of the year, the mean monthly temperature in
northern Illinois is 74° F. as compared to 80° F. for the southern part of the state.
During January, the coldest month of the year, the mean for the extreme north is
20° F. as contrasted with 37° F. in the south. The July difference in means, shown
from the above, is 6 degrees, while the January difference is 17 degrees.
The range in the mean monthly maximum temperatures and the mean monthly
minimum temperatures also shows north-south variation, as will be noted from the
data for selected stations on the map. However, it can be observed that a greater
latitudinal difference exists between the mean monthly maximum values than be-
tween the mean monthly minimum values. Only slight local irregularities affect the
uniform east-west orientation of the isotherms in all months.
The uniformity of temperatures over the state during the warmer half-year is
indicated by the fact that an average of 28 to 30 days with a maximum temperature
above 90° F. is recorded in northern Illinois, while 35 to 40 days above 90° F. are noted
in southern Illinois. However, a greater areal variation in temperatures during the
winter is reflected by the average number of days with minimum temperatures below
0° F. These average 2 days in southern Illinois, 8 in central Illinois, and 12 in the
north.
40
MEAN JULY TEMPERATURES
Illinois State Woter Survey
HEATING AND COOLING DEGREE DAYS
Stanley Chaiign*:);,, ^i.
Heating and cooling degree days are units designed for measuring heating and
cooling requirements. Calculating limits of 65° and 75° F. were selected as points of
reference in the temperature scale where heating or cooling are necessary to maintain
comfort. For instance, where the daily mean temperature is below 65° F., heating is
necessary to maintain conditions of comfort for normal activities in any type of
roofed enclosure. The map presentation can be used to illustrate the need for con-
siderably more cooling volume in air conditioning systems in southern Illinois than in
the north.
Heating degree days are computed directly from mean temperatures and, conse-
quently, have a latitudinal distribution in Illinois. They are determined by sub-
tracting the daily mean temperature from 65 degrees and counting every degree of
difference as. one degree day. For instance, a day with a 54° F. mean temperature is
counted as 11 degree days. A low number of degree days exists in southern Illinois,
normally less than 4000 per year, while a high of over 7000 per year is recorded, on
the average, for the extreme northwestern part of the state. Except for local irregulari-
ties, the monthly distributions also reveal a south- to-north increase. January has the
highest monthly averages and July has the lowest. No degree days are recorded for
three months of the year, on the average, in southern Illinois. On the other hand, heat-
ing degree days are reported for all months in the north.
Cooling degree days also reveal a distinct latitudinal distribution in the state.
However, the north-south range from 100 to 600 cooling degree days annually is
greater percentagewise than the heating degree day range of from 4000 to 7000 over
the same area. Cooling degree days are computed by subtracting 75 degrees from the
daily mean temperature. Every degree of difference calculated on this basis is counted
as a cooling degree day. July is the month with the most cooling degree days, while
several of the colder months record no cooling degree days whatever. Cooling degree
days are recorded, on the average, during five months of the year in northern Illinois
and seven months of the year in the south.
:ari...
Average Annua
HEATING DEGREE DAYS
With Average Monthly Number
at Selected Locations
Illinois State Water Survey
Average Annual
COOLING DEGREE DAYS'
With Average Monthly Number
at Selected Locations
Deoree Doy,
Unltun 100
100-200
JOO-300
300-400
400-JOO
SOO-600
400-700
•»~.ogt ol
»» r—ri, o«»«./loh<,-
;x~t!T.::;".';:7:r;jl''7s°
GROWING SEASON
Stanley Changnon, Jr.
The average length of the growing season conforms to temperature distributions
in Illinois with a north-to-south increase in the length of the period. However, the
Mississippi, Wabash, and Illinois River valleys appear to influence the growing season
pattern by increasing the length of the season along their courses, as may be noted on
the map.
The average length of the growing season is defined as the number of days be-
tween the last average date of killing frost in the spring and the first average date of
killing frost in the fall. Average dates for the fall frost vary from early October in
northern Illinois to late October in the south. Average dates for the spring also show
a latitudinal variation, but the north-to-south difference is greater at this period than
in the fall. In southern Illinois, the end of March is normally the time of the last kill-
ing frost, while the end of the first week in May is the comparable period for the last
killing frost in the north. The local influence of Lake Michigan and the Chicago urban
area cause the eastern portion of Cook County to have a slightly longer growing sea-
son than the surrounding territory.
Dates of killing frosts can vary considerably from year to year, thus producing
growing seasons of varying lengths. For instance, at Springfield the average growing
season is 187 days, but there has been a season with 138 days, the shortest on record,
and one with 231 days, the longest on record. On the average, the earliest dates on
record for killing frosts in the fall are 29 days before the average frost dates. In the
spring, the latest dates of killing frost on record are, on the average, 31 days after the
average dates of killing frost.
The probabilities of the last killing frost of spring and the first killing frost of fall
having occurred by particular dates are indicated for selected locations in the ac-
companying tables. As an example, the last killing frost of spring will have occurred
at Chicago by April 16 in 50 percent of the years.
Chance of Last Killing Frost of Spring Having Occurred by a Particular Date
Percent Chance 0% 25% 50% 75%o lOO^o
Chicago Mar. 20 Apr. 6 Apr. 16 Apr. 22 May 23
Peoria Mar. 28 Apr. 9 Apr. 15 Apr. 23 May 9
Springfield Mar. 22 Apr. 3 Apr. 15 Apr. 16 May 25
Mt. Vernon Mar. 20 Apr. 9 Apr. 16 Apr. 23 May 7
Cairo Mar. 3 Mar. 17 Mar. 30 Apr. 7 Apr. 24
Chance of First Killing Frost of Fall Having Occurred by a Particular Date
Percent Chance 0% 25%o 50%o 75%o ^00%
Chicago Sept. 25 Oct. 14 Oct. 21 Nov. 4 Nov. 24
Peoria Sept. 26 Oct. 12 Oct. 20 Oct. 29 Nov. 12
Springfield Sept. 26 Oct. 12 Oct. 19 Nov. 1 Nov. 23
Mt. Vernon Sept. 15 Oct. 12 Oct. 22 Oct. 28 Nov. 10
Cairo Sept. 30 Oct. 24 Oct. 29 Nov. 9 Nov. 27
44
I Planning and Devel
Average Length of
GROWING SEASON
With Average Dates
of Killing Frost
Stote Water Survey
of Days
^
150140
160170
170-180
180190
Yfffffj,
190-200
B
200-210
210-220
April 21 "
Av.rag. doU o»
lort hilling f,o.l
-Av.rao. dol. o(
fWsl liilling Iroo
'Lu>.jJ L-
J« " 'I*
ILLINOIS WATER RIGHTS LAW
The availability of water for industrial and other uses includes consideration
of not only the presence or absence of water in an area but also of the permissive
and restrictive water rights laws which govern the use of the water that does exist.
In Western states extensive litigation and conflict over these questions has
been brought about because of severe shortages of water. Illinois has been spared
many of these difficulties in the past because the state has had an adequate supply
of water. This bounty has led to a relatively meager set of water laws and many
questions cannot be answered with authority. Nevertheless the implications for
agricultural, industrial, and municipal development and economic growth inherent
in these laws are obvious. The following is a brief summary of pertinent aspects
of Illinois Water Rights Law. *
American Water Law
Although the modern scientist views water in terms of the hydrologic cycle
and sees all aspects of water as part of a single pattern, the law, largely for historical
reasons, has created artificial classifications for handling water disputes. Different
rules have developed for water in natural watercourses (rivers, streams, and lakes),
for diflfused surface water, and for ground water (really underground or subterranean
water, called percolating water if it is not a well-defined underground stream) .
The 31 Eastern states follow the riparian doctrine as to water in natural water-
courses; the 17 Western states follow the prior appropriation doctrine. The former
doctrine is based on the idea that the water can be used only by those individuals
who own land bordering on the river, stream, or lake or by someone who has ob-
tained permission from such owner. This means that water is treated, in essence,
as a private property right, although each owner has only the use of the water rather
than the absolute possessory right. The latter doctrine is based on ownership by
the people or the state, with permission to use granted as a property right on the
basis of priority in time. Both broad doctrines have various interpretations; thus,
riparian rights may follow the reasonable use theory or the natural flow theory
or a combination of the two.
Ground water, too, is subject to varying legal theories. The Eastern states
usually follow the English rule of absolute ownership by the surface owner, some
carrying the rule so far that even malicious use by the owner is privileged. Others
say the use must be reasonable and prohibit use away from the surface land if it
*This statement is extracted from a 73-page report prepared on this topic by Professor John E. Cribbet for
the Water Resources Committee of the Illinois State Chamber of Commerce, dated January 1958. The full report,
available for $1.00 at the Illinois State Chamber of Commerce, 20 North Wacker Drive, Chicago, should be used
by anyone to whom the use of vv-ater is of vital concern.
4h
unreasonably harms a neighboring owner. Many of the Western states have adopted
some version of the appropriation doctrine even for ground water and California has
developed a new concept, entitled the correlative rights doctrine.
Diffused surface water, flowing off the land after rains or snow melt, has not
raised any serious questions as to use and it is generally assumed that an owner
can make any use he desires of water which falls on his own land. The major prob-
lem here has been how to get rid of surface water, i.e., drainage. Again, various
theories have evolved, the two principal ones being the common enemy rule and the
civil law rule of Roman Law adapted to the American scene, in Illinois modified and
augmented by a modern Drainage Code.
Illinois Water Law— the Common Law
Illinois is a strong common-law state, i.e., it is committed to the legal principles
laid down by the English and early American judicial decisions.
Water Rights Law Pertaining to Water in Natural Watercourses. The cases con-
cerning water in natural watercourses have tended to deal with matters of pollution
and diversion rather than consumption, but there are a sufficient number of decisions
to form at least a working base. Illinois follows the common-law riparian rights
doctrine as interpreted by both the natural flow and the reasonable use theories. It
has expressly repudiated the doctrine of prior appropriation and has recognized the
inadequacy of the natural flow theory as a test for all riparian rights.
Under the riparian doctrine water uses are divided into natural and artificial
uses. Natural uses represent needs that must be supplied if man is to e.xist — drinking
purposes, household wants, and water for his cattle or stock. For such purposes
a riparian owner may take all of the water he actually needs. On the other hand,
artificial uses are those which supply the comfort and increase the prosperity of
the landowner — such as irrigating lands or industrial applications. Water for arti-
ficial uses must be on a reasonable basis and one owner can not deprive another
of a proportionate use of the water for this purpose. In diversion cases the natural
flow theory may still prevail, but for pollution and consumption the reasonable use
test is more frequently used. The decisions distinguish between natural and arti-
ficial uses of water and place both industrial and agricultural uses in the latter class
but do not establish any priority between them.
All water rights are recognized as vested property rights and the owner can not
be deprived of them except by due process of law. This means that such rights must
be bargained for like any other property interest or taken by condemnation pro-
ceedings after due compensation is paid. Condemnation can take place only if the
taker has the power of eminent domain. Municipalities are treated like any other
riparian owner, except that they have the power to condemn.
Water Rights Law Pertaining to Ground Water. The Illinois law of ground water
rests on a single case decided in 1899 (Edwards v. Haeger) which places the state
in the list of those following the English common law. In the basic case the court
held that "Water which is the result of natural and ordinary percolation through the
soil is part of the land itself and belongs absolutely to the owner of the land, and,
in the absence of any grant, he may intercept or impede such underground per-
colations, though the result be to interfere with the source of supply of springs or
wells on adjoining premises." However, the owner may not maliciously injure his
neighbor. In the proper case Illinois would probably modify this view by a doctrine
of reasonable use.
Illinois Water Law— Legislation
The water legislation in Illinois is varied in scope. The bulk of the legislation
relates to such matters as drainage, navigation, pollution, and sanitation; areas
that have an indirect impact on the problems of water consumption. A few statutes
have a direct bearing on consumption.
Legal duties, powers, and functions are spread among a number of governmental
units, from local districts to various departments of the state government. Details
of such statutory law are available, but are beyond the scope of this summary.
Use of Lake Michigan Water
The law relating to the use of Lake Michigan water is not discussed here ex-
cept as the normal doctrine of riparian rights applies to that body of water. This
important subject is excluded because it involves not only local and state considera-
tions but also interstate, federal, and international (United States and Canadian)
policies and arguments.
48
MAJOR STATE AGENCIES DEALING WITH WATER SUPPLIES
There are several state agencies which have major responsibilities for the investigation,
development, and protection of water resources and the services of these agencies are available
for consultation on many types of water problems. The agencies mentioned below are those
with primary responsibilities in water resources, although there are other state agencies with
an interest in water.
Water Survey Division and Geological Survey Division of the Department of Registration and Education,
Urbana, Illinois. The Water Survey studies many aspects of the nature and extent of the state's
water resources, including ground water levels, precipitation, surface water supplies, stream
gaging, and siltation of water impoundment reservoirs. Information on the mineral quality
of water and engineering information about well yields and water levels can be secured from
this source. The Geological Survey deals with the geological aspects of ground water supply.
These two agencies work closely together and have a storehouse of information available
to all interested persons on most aspects of local water supplies.
Division of Waterways of the Department of Public Works and Buildings, Springfield, Illinois. This
agency has general supervision of all public bodies of water in the state, including those lakes,
streams, canals, and rivers not owned by private interests, municipal corporations, or the
United States Government. It administers more than 50 laws and regulations which protect
the public interests in these waters. It regulates construction in public waters, prevents ob-
struction of navigation in navigable watercourses, supervises planning and construction of
flood control works, operates moveable bridges over the Illinois waterway and makes general
surveys and investigations of Illinois watercourses.
Division of Sanitary Engineering of the Department of Public Health, Springfield, Illinois. Among other
activities, this division acts in a supervisory capacity relative to the sanitary quality, mineral
quality, and adequacy of proposed and existing public water supplies, treatment, and purifica-
tion works. The division also supplies the technical staff for the administrative activities of the
Sanitary Water Board.
The Sanitary Water Bosurd is charged "to control, prevent, and abate pollution of the
streams, lakes, ponds, and other surface and underground waters in the state. . . ." Among the
functions of the board are: reviewing plans and specifications for proposed domestic and
industrial waste treatment works operation, making necessary investigations and reports
upon natural waters, and conducting all other activities pertinent to a successful stream
sanitation and conservation program.
Division of Oil and Gas of the Department of Mines and Minerals, Springfield, Illinois. This
division has jurisdiction over pollution of land and water resulting from oil field operations
and issues permits for rock water wells.
SELECTED REFERENCE LIST OF DOCUMENTS
PERTAINING TO WATER RESOURCES
Public Ground-Water Supplies in Illinois. Bull. 40, 1950.
New Public Ground-Water Supplies 1950-1957. Suppl. I, Bull. 40, 1958.
Quality of Surface Waters in Illinois. Bull. 45, 1958.
Rainfall Relations on Small Areas in Illinois. Bull. 44, 1957.
1952-55 Illinois Drought with Special Reference to Impounding Reservoir Design.
Bull. 43, 1955.
Water and Land Resources of the Crab Orchard Lake Basin. With U.S. Fish and Wild-
life Serv., U.S. Soil Conserv. Serv., Southern 111. Univ., 111. Agric. Experiment Sta. Bull.
42, 1954.
Ground Water in the Peoria Region. With 111. State Geol. Survey. Bull. 39, 1950.
Causes and Effects of Sedimentation in Lake Decatur. With U.S. Soil Conserv. Serv.,
111. Agric. Experiment Sta. Bull. 37, 1947.
Preliminary Data on Surface -Water Resources. Bull. 31, 1937.
Potential Water Resources of Southern Illinois. Rep. Investigation 31, 1957.
Trends in Residential Water Use. Rep. Investigation 30, 1956.
Preliminary Investigation of Ground-Water Resources in the American Bottom in
Madison and St. Clair Counties, Illinois. Rep. Investigation 17, 1953.
Temperature and Turbidity of Some River Waters in Illinois. Rep. of Investigation 1,
1948.
High-Rate Recharge of Ground Water by Infiltration. Circ. 54, 1956.
Evaporation Records in Illinois. Circ. 43, 1953.
Mineral Content of Public Ground-Water Supplies in Illinois. Circ. 31, 1951.
Chicago Area Water Supply. Circ. 29, 1950.
Local Climatological Data for Rockford, Monmouth, Urbana, and Mount Vernon. With
U.S. Weather Bureau. 1955.
Physiographic Divisions of Illinois. Rep. Investigation 129, 1948.
Water Wells for Farm Supply in Central and Eastern Illinois. Circ. 192, 1954.
Ground Water Possibilities in Northeastern Illinois. Circ. 198, 1955.
Ground Water in Northwestern Illinois. Circ. 207, 1956.
Ground Water Geology in Southern Illinois, A Preliminary Geologic Report. Circ.
212, 1956.
Ground Water Geology in Western Illinois, North Part. Circ. 222, 1956.
Ground Water Geology in South Central Illinois. Circ. 225, 1957.
Ground Water Geology in Western Illinois, South Part. Circ. 232, 1957.
Ground Water Geology in East Central Illinois. Circ. 248, 1958.
Stream Flow Data of Illinois. With U.S. Geol. Survey, 1937.
Unit Hydrographs in Illinois. With U.S. Geol. Survey, 1948.
Water Supply Characteristics of Iminois Streams. With U.S. CJcol. Survey, 1950.
Floods in Illinois: Magnitude and Frequency. With U.S. Geol. Survey, 1954.
Flow Duration of Illinois Streams. With U.S. Geol. Survey, 1957.
Climate of Illinois, Summary and Analysis of Long-Timc Weather Records. Bull. 532, 111.
Agric. Experiment Sta., 1949.
Illinois Water Use L.wv. Coll. of Agric. with U.S. Agric. Research Scrv. Res. rep. AERR19,
1957.
Water Supply Papers (referring to Illinois).
Bibliography: Nos. 427, 563, 564, 565, 1492.
Surface waters: Nos. 563, 564, 565 and 194, 239, 44, 1278, 1337, 1338, 1387.
Stream measurements: Nos. 83, 98, 128, 171, 207, 245, 265, 285, 305, 325, 355, 385,
405, 435, 455, 475, 505, 525, 545, 565, 585, 605, 625, 645, 665, 685, 700, 715, 730, 745, 760,
785,805,825,855,875,895,925,975, 1005, 1035, 1055, 1085, 1115, 1145, 1175, 1278.
Underground waters, artesian pressure: Nos. 908, 938, 946, 988, 1018, 1025, 1073, 1098,
1128, 1158, 1167.
Quality: Nos. 239, 1186.
Southwestern Illinois: No. 164.
Springs: Nos. 114, 164.
Wells: Nos. 57, 114, 149, 164, 364, 946.
Illinois Water Supply, A Report on the Water Resources oi Illinois. 1956.
I LLiNOis Water Rights Law and What Should Be Done About It, A Research Report. 1958.
Proceedings of a Statewide Conference on Local Water Supply Problems, Peoria,
Illinois. 1957.
Data on Public W.vrER Supplies in Incorporated Municipalities. Circ. N846, 1956.
The Industrial Potential of Southern Illinois. Southern Illinois Univ., 1954.
Statewide Conservation Lake Construction Program. 111. Department of Conserv, 1947.
Water Quality and Flow Variations in the Ohio Rivkr, 1951-55. Ohio River Valley
Sanitation Commission, 1957.
Water U.se in the United States, 1900-1975. I'.S. Department of Conunerce, 1956.
Report of the Illinois Water and Drouth Study Commission. 70th General A.sscmbly,
1957.
Story of the Metropolitan Sanitary Di.strict of Gre.vier Chic.\go. Metropolitan
Sanitary District of Greater Chicago, 1956.
Industrial Operations Under Extremes of Weather. Meteorological Mono., Vol. 2,
No. 9, Am. Metcorol. Soc, May, 1957.
Publications of llie U.S. Weather burc.in ami the U.S. (ieological Survey are among the
major sources of reference consulted in the compilation of this atlas.
GLOSSARY FOR WATER RESOURCES AND CLIMATE
Acre-Foot. A term used in measuring the volume of water, equal to the quantity of water re-
quired to cover an acre 1 foot in depth, or 43,560 cubic feet.
Aquifer. A geologic formation that is water-bearing and which transmits water from one
point to another.
Artesian Aquifer. A soil or rock formation which is confined above and below and in which
water is under pressure.
Cubic Foot per Second. A unit of discharge for measurement of flowing liquid, equal to a flow
of one cubic foot per second past a given section. Also called Second Foot.
Dam. A barrier constructed across a water course for the purpose of (1) creating a reservoir,
(2) diverting water from a conduit or channel, (3) creating a head which can be used to
generate power, and (4) improving river navigability.
Drainage. An area from which surface runoff is carried away by a single drainage system.
Also called Watershed and Drainage Area.
Drawdown. The change in surface elevation of a body of water as a result of the withdrawal
of water.
Flood. A relatively high flow as measured by either gage height or discharge quantity.
Ground Water. Subsurface water occupying the zone of saturation. In a strict sense the term
applies only to water below the water table.
Hardness. A characteristic of water, chiefly due to the existence therein of the carbonates
and sulfates and occasionally the nitrates and chlorides of calcium, iron, and magnesium.
It is commonly computed from the amounts of calcium and magnesium in the water and
expressed as equivalent calcium carbonate.
Head. The vertical height of a water column or its equivalent pressure in other units.
Hydrology. The applied science concerned with the waters of the earth — their occurrences,
distribution, and circulation through the hydrologic cycle.
Hydrologic Cycle. A complete cycle through which water passes, commencing as atmospheric
water vapor, passing into liquid and solid form as precipitation, thence along or into the
ground surface, and finally again returning to the atmosphere as water vapor by means of
evaporation and transpiration.
Impervious. A term applied to a material through which water cannot pass. It is also applied
to material through which water passes with great difficulty.
Intake. The surface area upon which water that eventually reaches an aquifer or ground
water basin is initially absorbed. Also called Catchment Area.
Irrigation. The artificial application of water to lands for agricultural purposes.
Permeability. The property of the material which permits appreciable movement of water
through it when saturated and actuated by hydrostatic pressure of a magnitude normally
encountered in natural subsurface water.
Reservoir. A pond, lake, tank, basin, or other space, either natural or created in whole or in
part by the building of engineering structures, which is used for storage, regulation, and
control of water.
Sedimentation. The process of subsidence and deposition of suspended matter carried by water.
It is usually due to a reduction of the velocity of water below the point where the suspended
material can be transported.
Till. Deposits of glacial drift laid down in place as the glacier melts. These deposits are
unsorted and unstratified rock, flour, sand, pebbles, cobbles, and boulders.
Transmissibility. The number of gallons of water a day that percolate under prevailing condi-
tions through each square mile of water-bearing bed for each foot thickness of bed.
Transpiration. A process by which plants dissipate water into the atmosphere from their
leaves and other surfaces.
Water-Bearing. A term, more or less relative, used to designate a formation that contains
considerable ground water. It is usually applied to formations from which the ground water
may be extracted by pumping, drainage, etc.
^one oj Saturation. The zone below the water table in which pores of the soil are completely
saturated with water.
Colder HalJ-Tear. A period of six months including October, November, December, January,
February, and March.
Degree Days, Cooling. These units are used to give an index for cooling requirements and are
computed for each day by subtracting 75 degrees from the daily mean temperature
(Fahrenheit).
Degree Days, Heating. These units are used to give an index for heating requirements and are
computed for each day by subtracting the daily mean temperature from 65 degrees
(Fahrenheit) .
Glaze. Rain that falls in liquid form and freezes to objects on the ground. .-Mso known as
freezing rain and often referred to as ice storms.
Growing Season. This period is the number of days between the last spring date with a tempera-
ture of 32° F. or lower and the first fall date with a temperature of 32° F. or lower.
Isotherm. A line on the earth's surface joining points of the same temperature at a given time
or for a given period.
Mean Monthly Maximum Temperature. This is computed by adding all the daily maximum
temperatures in the month and dividing this total by the number of days in the month.
Mean Monthly Minimum Temperature. This is computed by adding all the daily minimum
temperatures in the month and dividing this total by the number of days in the month.
Mean Monthly Temperature. This is computed by adding the mean monthly maximum tem-
perature and the mean monthly minimum temperature and dividing this total by two.
Nocturnal Thunderstorms. Thunderstorms that occur at night.
Precipitation. All water which falls to the earth's surface, including hail, snow, and sleet as
well as rainfall.
Sleet. Transparent grains of ice formed by raindrops freezing as they fall.
Snow. White or transparent ice crystals, often in complex hexagonal forms.
Warmer Hatf-Tear. A period of six months including April, May, June, July, August, and
September.
INDEX OF COUNTIES, CITIES, AND TOWNS
Incorporated Cities and Towns with Populations of 1000 or more in 1950
County
Map
Coordinate
County
Map
Coordinate
County
Map
Coordinate
Map
Coordinate
Adams
A-8
Ford
G-6
Livingston
G-5
Randolph
D-13
Alexander
E-16
Franklin
F-1 3
Logan
E-7
Richland
H-11
Bond
E-n
Fulton
D-6
McDonough
B-6
Rock Island
B-4
Boone
F-1
Gallatin
H-14
McHenry
G-1
St. Clair
D-12
Brown
B-8
Greene
C-10
McLean
F-6
Saline
G-1 4
Bureau
E-4
Grundy
G-4
Macon
F-8
Sangamon
E-9
Calhoun
B-10
Hamilton
G-13
Macoupin
D-10
Schuyler
C-7
Carroll
D-2
Hancock
A-7
Madison
D-11
Scott
C-9
Cass
C-8
Hardin
H-15
Marion
F-12
Shelby
G-10
Champaign
H-7
Henderson
B-5
Marshall
F-5
Stark
D-5
Christian
E-9
Henry
D-4
Mason
D-7
Stephenson
E-1
Clark
J-10
Iroquois
J-6
Massac
F-16
Tazewell
E-6
Clay
G-11
Jackson
E-14
Menard
D-8
Union
E-1 5
Clinton
E-12
Jasper
H-10
Mercer
B-4
Vermilion
J-7
Coles
H-9
Jefferson
F-1 3
Monroe
C-1 3
Wabash
J-12
Cook
J-2
Jersey
C-10
Montgomery
E-10
Warren
C-6
Crawford
J-"
Jo Daviess
C-1
Morgan
C-8
Washington
E-12
Cumberland
H-10
Johnson
F-1 5
Moultrie
G-9
Wayne
G-1 2
DeKalb
F-2
Kane
G-2
Ogle
E-2
White
H-1 3
De Witt
F-7
Kankakee
H-4
Peoria
D-5
Whiteside
D-3
Douglas
H-8
Kendall
G-3
Perry
E-13
Will
H-4
Du Page
H-2
Knox
C-5
Piatt
G-8
Williamson
F-14
Edgar
J-9
Lake
H-1
Pike
B-9
Winnebago
F-1
Edwards
H-12
La Salle
F-4
Pope
G-1 5
Woodford
F-5
Effingham
G-10
Lawrence
J-11
Pulaski
F-16
Fayette
F-10
Lee
E-3
Putnam
E-4
CiTKs AND Towns
Map
Coordinate
County
Map
Coordinat
Population County
Abington
C-5
3,330
Knox
Auburn
D-9
1,963
Sangamon
Albion *
H-12
2,287
Edwards
Aurora
G-3
50,576
Kane
Aledo*
B-4
2,919
Mercer
Harrington
H-1
4,209
Cook-Lake
Algonquin
G-1
1,223
McHenry
Barry
B-9
1,529
Pike
Alorton
C-1 2
2,547
St. Clair
Bartonville
E-6
2,437
Peoria
Alsip
J-3
1,228
Cook
Batavia
G-2
5,838
Kane
Altamont
G-10
1,580
Effingham
Beardstown
C-8
6,080
Cass
Alton
C-11
32,550
Madison
Beckemeyer
E-12
1,045
Clinton
Amboy
E-3
2,128
Lee
BellevUle*
D-12
32,721
St. Clair
Anna
E-1 5
4,380
Union
Bellevue
E-6
1,529
Peoria
Antioch
H-1
1,307
Lake
Bellwood
H-2
8,746
Cook
Areola
G-9
1,700
Douglas
Belvidere *
F-1
9,422
Boone
Arlington Hts.
H-2
8,768
Cook
Bement
G-8
1,459
Piatt
Arthur
G-8
1,573
Douglas-
Benld
D-10
2,093
Macoupin
Moultrie
Bensenville
H-2
3,754
Du Page
Ashland
D-8
1,039
Cass
Benton *
F-1 3
7,848
Franklin
Assumption
F-9
1,466
Christian
Berkeley
H-2
1,882
Cook
Astoria
C-7
1,308
Fulton
Berwyn
J-2
51,280
Cook
Athens
D-8
1,048
Menard
Bethalto
D-11
2,115
Madison
Atlanta
E-7
1,331
Logan
Bloomington *
F-6
34,163
McLean
;/
*(
County Seat
Place
.Uap
CoordinaU
Population
County
Placf
Map
Coordinate
Population
County
Blue Island
J-3
17,622
Cook
Dallas City
A-6
1,275
Hancock-
Bourbonnais
H-4
1,598
Kankakee
Henderson
Bradley
H-4
5,699
Kankakee
Danville *
J-7
37,864
Vermilion
Braidwood
H-4
1,485
Will
Decatur *
F-8
66,269
Macon
Breese
E-12
2,181
Clinton
Deerfield
J-1
3,288
Lake
Bridgeport
J-11
2,358
Lawrence
De Kalb
G-2
11,708
De Kalb
BridgeView
J-3
1,393
Cook
Delavan
E-7
1,248
Tazewell
Broadview
H-2
5,196
Cook
Depue
E-4
2,163
Bureau
Brookfield
H-2
15,472
Cook
Dcs Plaincs
H-2
14,994
Cook
Brooklyn
C-12
2,568
St. Clair
Divernon
E-9
1,013
Sangamon
Brookport
G-16
1,119
Massac
Dixmoor
J-3
1,327
Cook
Bunker Hill
D-11
1,238
Macoupin
Dixon *
E-2
11,523
Lee
Burnham
J-3
1,331
Cook
Dolton
J-3
5,558
Cook
Bushnell
C-6
3,317
McDonough
Downers Grove
H-3
11,886
Du Page
Byron
E-1
1,237
Ogle
Dupo
C-12
2,239
St. Clair
Cairo*
F-16
12,123
Alexander
Du Quoin
E-14
7,147
Perry
Calumet City
J-3
15,799
Cook
Dwight
G-5
2,843
Livingston
Calumet Park
J-3
2,500
Cook
EarlviUe
F-3
1,217
La Salle
Cambridge *
C-4
1,489
Henry
East Alton
D-II
7,290
Madison
Canton
D-6
11,927
Fulton
East Chicago Hts.
J-3
1,548
Cook
Carbondale
F-I4
10,921
Jackson
East Dubuque
C-1
1,697
Jo Daviess
Carlinville*
D-10
5,116
Macoupin
East Dundee
H-2
1,466
Kane
Carlyle*
E-12
2,669
Clinton
East Hazel Crest
J-3
1,066
Cook
Car mi*
H-13
5,574
White
East Moline
C-3
13,913
Rock Island
Carpentersvillc
H-2
1,523
Kane
East Peoria
E-5
8,698
Tazewell
Carrier Mills
G-14
2,252
Saline
East St. Louis
C-12
82,295
St. Clair
CarroUton •
C-10
2,437
Greene
Edwardsville *
D-11
8,776
Madison
Carter ville
F-14
2,716
Williamson
Effingham*
G-10
6,892
Effingham
Carthage*
A-7
3,214
Hancock
Eldorado
G-14
4,500
Saline
Casey
H-10
2,734
Clark
Elgin
G-2
44,223
Cook-Kane
Cascyville
D-12
1,209
St. Clair
Elmhurst
H-2
21,273
Du Page
Central City
F-12
1,231
Marion
Elmwood
D.5
1,613
Peoria
Centralia
F-12
13,863
Clinton-
Elmwood Park
J-2
18,801
Cook
Marion
El Paso
F-6
1,818
Woodford
Ccrro Gordo
G-8
1,052
Piatt
Erie
D-3
1,180
Whiteside
Champaign
H-7
39,563
Champaign
Eureka*
E.6
2,367
Woodford
Charleston *
H-9
9,164
Coles
Evanston
J-2
73,641
Cook
Chatsworth
G-6
1,119
Livingston
Evergreen Park
J-3
10,531
Cook
Chenoa
G-6
1,452
McLean
Fairbury
G-6
2,433
Livingston
Chester *
D-14
5,389
Randolph
Fairfield*
G-12
5,576
Wayne
Chicago*
J-2
3,620,962
Cook
Fairmont City
D-12
2,284
St. Clair
Chicago Hts.
J-3
24,551
Cook
Farmer City
G-7
1,752
De Witt
ChUlicothe
E-5
2,767
Peoria
Farmington
D.6
2,651
Fulton
Chrisman
J-8
1,071
Edgar
Flora
G-12
5,255
Clay
Christopher
F-14
3,545
Franklin
Flossmoor
J-3
1,804
Cook
Cicero
J-2
67,544
Cook
Forest Park
J-2
14,969
Cook
Clarendon HUls
H-3
2,437
Du Page
Forrest
G-5
1,040
Livingston
Clay City
G-11
1,103
Clay
Forreston
E-2
1,048
Ogle
Clinton *
F-7
5,945
De Witt
Fox Lake
H-1
2,238
Lake
Coal City
G-4
2,220
Grundy
Fox River Grove
H-1
3,313
McHenry
Cobden
E-1 5
1,104
Union
Franklin Park
H-2
8,899
Cook
Colchester
B-7
1,551
McDonough
Frecburg
D-12
1,661
St. Clair
Collinsville
D-12
11,862
Madison-
Freeport *
E-1
22,467
Stephenson
St. Clair
Fulton
D-2
2,706
Whiteside
Columbia
C-12
2,179
Monroe
Galena *
C-1
4,648
Jo Daviess
Coulterville
E-13
1,160
Randolph
Galesburg*
C-5
31,425
Knox
Crete
J-3
2,298
Will
Galva
D-4
2,886
Henry
Creve Coeur
E-6
5,499
Tazewell
Gcneseo
D-3
4,325
Henry
Crotty
G-4
1,435
La Salle
Geneva*
G-2
5.139
Kane
Crystal Lake
G-1
4,832
McHcnry
Genoa
G-2
1,690
DcKalb
Cuba
C-6
1,482
Fulton
Georgetown
J-8
3,294
Vermilion
• Count)
• Seat
55
Place
Map
Coordinate
Population
County
Place
Map
Coordinate
Population
County
Gibson
G-6
3,029
Ford
LawrenccviUe *
J-Il
6,328
LaviTence
Gillespie
D-10
4,105
Macoupin
Lebanon
D-12
2,417
St. Clair
Gilman
H-5
1,602
Iroquois
Lemont
H-3
2,757
Cook
Girard
D-9
1,740
Macoupin
Lena
D-1
1,227
Stephenson
Glen Carbon
D-11
1,176
Madison
Le Roy
F-7
1,820
McLean
Glencoe
J-1
6,980
Cook
Lcwistown *
D-7
2,630
Fulton
Glen EUyn
H-2
9,524
Du Page
Lexington
F-6
1,181
McLean
Glenview
J-2
6,142
Cook
Libertyville
H-1
5,425
Lake
Golconda *
G-15
1,066
Pope
Lincoln *
E-7
14,362
Logan
Grafton
C-11
1,117
Jersey
Lincolnwood
J-2
3,072
Cook
Grandview
E-8
1,349
Sangamon
Litchfield
E-1
7,208
Montgomery
Granite City
C-12
29,465
Madison
Lockport
H-3
4,955
Will
Grays Lake
H-1
1,970
Lake
Lombard
H-2
9,817
Du Page
Grayville
H-13
2,461
White-
Loves Park
F-1
5,366
Winnebago
Edwards
Lovington
G-9
1,152
Moultrie
Greenup
H-10
1,360
Cumberland
Lyons
J-2
6,120
Cook
Greenville*
E-11
4,069
Bond
McHenry
H-1
2,080
McHenry
Griggs ville
B-9
1,199
Pike
McLeansboro *
G-1 3
3,008
Hamilton
Gurnee
H-1
1,097
Lake
Mackinaw
E-6
1,011
Tazewell
Hamilton
A-7
1,776
Hancock
Macomb*
B-6
10,592
McDonough
Hanover
C-1
1,643
Jo Daviess
Madison
C-12
7,963
Madison
Harrisburg*
G-14
10,999
Saline
Mahomet
G-7
1,017
Champaign
Hartford
D-U
1,909
Madison
Manteno
J-4
1,789
Kankakee
Harvard
G-1
3,464
McHenry
Marengo
G-1
2,726
McHenry
Harvey
J-3
20,683
Cook
Marion*
F-14
10,459
Williamson
Havana *
D-7
4,398
Mason
Marissa
D-1 3
1,652
St. Clair
Hazel Crest
J-3
2,129
Cook
Markham
J-3
2,753
Cook
Henry
E-5
1,966
Marshall
Maroa
F-8
1,100
Macon
Herrin
F-14
9,331
Williamson
Marseilles
G-4
4,514
La Salle
Heyworth
F-7
1,072
McLean
Marshall *
J-9
2,960
Clark
Highland
D-11
4,283
Madison
Martinsville
H-10
1,440
Clark
Highland Park
J-1
16,808
Lake
Mascoutah
D-12
3,009
St. Clair
Highwood
J-1
3,813
Lake
Mason City
D-7
2,004
Mason
Hillsboro*
E-10
4,141
Montgomery
Matteson
J-3
1,211
Cook
Hillside
H-2
2,131
Cook
Mattoon
G-9
17,547
Coles
Hinsdale
H-3
8,676
Du Page-
Maywood
J-2
27,473
Cook
Cook
Melrose Park
J-2
13,366
Cook
Homer
H-8
1,030
Champaign
Mendota
F-3
5,129
La Salle
Homewood
J-3
5,887
Cook
Merrionette Park
J-3
1,101
Cook
Hoopeston
J-6
5,992
Vermilion
Metamora
E-5
1,368
Woodford
Itasca
H-2
1,274
Du Page
Metropolis *
G-1 6
6,093
Massac
Jacksonville *
C-9
20,387
Morgan
Midlothian
J-3
3,216
Cook
Jerseyville*
C-10
5,792
Jersey
Milan
C-4
1,737
Rock Island
Johnson City
F-U
4,479
Williamson
Milford
J-6
1,648
Iroquois
Joliet*
H-3
51,601
Will
MiUedgeville
D-2
1,044
Carroll
Jonesboro *
E-15
1,607
Union
Millstadt
D-12
1,566
St. Clair
Kankakee*
H-4
25,856
Kankakee
Minonk
F-5
1,955
Woodford
Keithsburg
B-5
1,006
Mercer
Moline
C-3
37,397
Rock Island
Kenilworth
J-2
2,789
Cook
Momence
J-4
2,644
Kankakee
Kewanee
D-4
16,821
Henry
Monmouth*
C-5
10,193
Warren
Kincaid
E-9
1,793
Christian
Monticello*
G-8
2,612
Piatt
Knoxville
C-5
2,209
Knox
Morris*
G-4
6,926
Grundy
Lacon *
E-5
2,020
Marshall
Morrison *
D-3
3,531
Whiteside
Ladd
F-3
1,224
Bureau
Morrisonville .
E-9
1,182
Christian
La Grange
H-2
12,002
Cook
Morton
E-6
3,692
Tazewell
La Grange Park
H-2
6,176
Cook
Morton Grove
J-2
3,926
Cook
La Harpe
B-6
1,295
Hancock
Mound City*
F-1 6
2,167
Pulaski
La Salle
F-4
12,083
La Salle
Mounds
F-1 6
2,001
Pulaski
Lake Bluff
J-1
2,000
Lake
Mount Carmel *
J-12
8,732
Wabash
Lake Forest
J-1
7,819
Lake
Mount Carroll *
D-2
1,950
Carroll
Lanark
D-2
1,359
Carroll
Mount Morris
E-2
2,709
Ogle
Lansing
J-3
8,682
Cook
Mount Olive
D-10
2,401
Macoupin
56
*Cour
ity Seat
Place
Map
Coordmatf
Population
County
Coordinate
Population
Counl\
Mount Prosprct
H-2
4,009
c:ook
Port Byron
C-3
1,050
Rock Island
Mount Pulaski
i:-8
1,526
Logan
Posen
J-3
1,795
Cook
Mount Sterling *
B.8
2,246
Brown
Princeton *
E-4
5,765
Bureau
Mount Vernon *
F-13
15,600
JefTerson
Princeville
D-5
1,113
Peoria
Moweaqua
F-9
1,475
Shelby
Prophctstown
D-3
1,691
Whiteside
Mundclein
H-1
3,189
Lake
Quincy *
A-8
41,450
Adams
Murphysboro *
F,-14
9,241
Jackson
Rantoul
H-7
6,387
Champaign
Naperville
H-3
7,013
Du Page
Red Bud
D-13
1,519
Randolph
Nashville*
E-13
2,432
Washington
Ridgway
H-14
1,148
Gallatin
Nauvoo
A-6
1,242
Hancock
Riverdale
J-3
5,840
Cook
Neoga
G-10
1,125
Cumberland
River Forest
J-2
10,823
Cook
New Athens
D-13
1,518
St. Clair
River Grove
J-2
4,839
Cook
New Baden
D-12
1,428
Clinton-
Riverside
H-2
9,153
Cook
St. Clair
River ton
E-8
1,450
Sangamon
New Lenox
H-3
1,235
Will
Roanoke
F-5
1,368
Woodford
Newman
H-8
1,140
Douglas
Robbins
J-3
4,766
Cook
Newton*
H-11
2,780
Jasper
Robinson *
J-11
6,407
Crawford
Niles
J-2
3,587
Cook
Rochelle
F-2
5,449
Ogle
Nokomis
E-10
2,544
Montgomery
Rockdale
H-3
1,393
Will
Normal
F-6
9,772
McLean
Rock Falls
D-3
7,983
Whiteside
Norridge
J-2
3,428
Cook
Rockford *
F-1
92,927
Winnebago
Norris City
G-14
1,370
White
Rock Island *
C-3
48,710
Rock Island
Northbrook
J-1
3,348
Cook
Rockton
F-1
1,432
Winnebago
North Chicago
J-1
8,628
Lake
Roodhouse
C-9
2,368
Greene
North Chillicothc
E-S
1,741
Peoria
Roselle
H-2
1,038
Du Page
Northfield
J-2
1,426
Cook
Roseville
B.6
1,080
Warren
North Lake
H-2
4,361
Cook
Rosiclarc
G-15
2,086
Hardin
North Pekin
E-6
1,758
Tazewell
Rossvillc
J-7
1,382
Vermilion
North Riverside
J-2
3,230
Cook
Round Lake Beach
H-1
1,892
Lake
Oak Forest
J-3
1,856
Cook
Round Lake Park
H-1
1,836
Lake
Oak Lawn
J-3
8,751
Cook
Roxana
D-U
1,911
Madison
Oak Park
J-2
63,529
Cook
Royal ton
F-14
1,506
Franklin
Oblong
H-11
1,639
Crawford
Rushville *
C-7
2,682
Schuyler
Odin
F-12
1,341
Marion
St. Anne
J-5
1,403
Kankakee
O'Fallon
D.12
3,022
St. Clair
St. Charles
G-2
6,709
Kane
Oglesby
F-4
3,922
La Salle
St. Elmo
F-11
1,716
Fayette
Olney*
H-11
8,612
Richland
St. FrancisviUc
J-12
1,117
Lawrence
Onarga
H-6
1,455
Iroquois
Salem*
F-12
6,159
Marion
Oregon •
E-2
3,205
Ogle
Sandoval
F-12
1,531
Marion
Oswego
G-3
1,220
Kendall
Sandwich
G-3
3,027
DcKalb
Ottawa •
F-4
16,957
La Salle
Savanna
D-2
5,058
Carroll
Palatine
H-2
4,079
Cook
Schiller Park
H-2
1,384
Cook
Palestine
J-11
1,589
Crawford
Sesser
F-13
2,086
Franklin
Pana
F-9
6,178
Christian
Shawnectown *
H-14
1,917
Gallatin
Paris*
J-9
9,460
Edgar
Shelbyville*
F-9
4,462
Shelby
Park Forest
J-3
8,130
Cook
Sheldon
J-5
1,114
Iroquois
Park Ridge
H-2
16,602
Cook
Silvis
C-3
3,055
Rock Island
Paxton •
H-6
3,795
Ford
Skokic
J-2
14,832
Cook
Pccatonica
E-1
1,438
Winnebago
South Bcloit
F-1
3,221
Winnebago
Pekin *
E-6
21,858
Tazewell
South Chicago Hts.
J-3
2,129
Cook
Peoria*
E-6
111,856
Peoria
South Elgin
G-2
1,220
Kane
Peoria Heights
E-6
5,425
Peoria
South Holland
J-3
3,247
Cook
Peotone
J-4
1,395
Will
South Jacksonville
C-9
1,165
Morgan
Peru
F-4
8,653
La Salle
South Pekin
E.6
1,043
Tazewell
Petersburg *
D-8
2,325
Menard
Sparta
D.13
3,576
Randolph
Phoenix
J-3
3,606
Cook
Springfield *
E-8
81,628
Sangamon
Pinckneyville *
E-13
3,299
Perry
Spring X'allcy
F-4
4.916
Bureau
Pittsfield*
B.9
3,564
Pike
Staunton
D-11
4,047
Macoupin
Plainfield
H-3
1,764
Will
Steel ville
i:-14
1,353
Randolph
Piano
G-3
2,154
Kendall
Stcgcr
J-3
4,358
Will-Cook
Polo
E-2
2,242
Ogle
Sterling
D-3
12,817
Whiteside
Pontiac *
G-5
8,990
Livingston
Stickney
J-2
3,317
Cook
• Count
y Scat
^7
Place
Map
Coordinate
Population
County
Place
Map
Coordinate
Population
County
Stockton
D-1
1,445
Jo Daviess
Wauconda
H-1
1,173
Lake
Stone Park
J-2
1,414
Cook
Waukegan *
J-1
38,946
Lake
Stonington
F-9
1,120
Christian
Wavcrly
D-9
1,330
Morgan
Streator
F-4
16,469
La Salle-
Wenona
F-5
1,005
Marshall
Livingston
Westchester
H-2
4,308
Cook
Sullivan *
G-9
3,470
Moultrie
West Chicago
H-2
3,973
Du Page
Summit
J-3
8,957
Cook
West City
F-14
1,081
Franklin
Sumner
J-11
1,170
Lawrence
West Dundee
H-2
1,948
Kane
Swansea
D-1 2
1,816
St. Clair
Western Springs
H-2
6,364
Cook
Sycamore *
G-2
5,912
De Kalb
West Frankfort
F-14
11,384
Franklin
Taylorville *
E-9
9,188
Christian
Westmont
H-3
3,402
Du Page
Thornton
J-3
1,217
Cook
Westville
J-8
3,196
Vermilion
Tilton
J-7
1,638
Vermilion
Wheaton *
H-2
11,638
Du Page
Tinley Park
J-3
2,326
Cook
White Hall
C-9
3,082
Greene
Tolono
H-8
1,065
Champaign
Willow Springs
H-3
1,314
Cook
Toluca
F-5
1,419
Marshall
Wilmette
J-2
18,162
Cook
Toulon *
D-5
1,173
Stark
Wilmington
H-4
3,354
Will
Tremont
E-6
1,138
Tazewell
Winchester*
C-9
1,591
Scott
Trenton
E-12
1,432
Clinton
Windsor
G-9
1,008
Shelby
Troy
D-11
1,260
Madison
Winnetka
J-2
12,105
Cook
Tuscola *
H-8
2,960
Douglas
Winthrop Harbor
J-2
1,765
Lake
Urbana*
H-7
22,834
Champaign
Witt
E-10
1,156
Montgomery
Vandalia *
F-11
5,471
Fayette
Wood Dale
H-2
1,857
Du Page
Venice
C-12
6,226
Madison
Wood River
D-11
10,190
Madison
Vienna*
F-15
1,085
Johnson
Woodstock *
G-1
7,192
McHenry
Villa Grove
H-8
2,026
Douglas
Worth
J-3
1,472
Cook
Villa Park
H-2
8,821
Du Page
Wyoming
D-5
1,496
Stark
Virden
D-9
3,206
Macoupin
Zeigler
F-14
2,516
Franklin
Virginia*
C-8
1,572
Cass
Zion
J-1
8,950
Lake
Walnut
E-3
1,093
Bureau-
Washington
County Seats WITH
Populations OF Less TH
ANl000iNl950
Wamac
F-12
1,429
Marion-
Clinton
Elizabethtown *
G-1 5
583
Hardin
Warren
D-1
1,378
Jo Daviess
Hardin *
C-10
928
Calhoun
Warsaw
A-7
2,002
Hancock
Hennepin *
E-4
312
Putnam
Washington
E-6
4,285
Tazewell
Louisville*
G-11
970
Clay
Washington Park
D-1 2
5,840
St. Clair
Oquawka *
B-5
929
Henderson
Waterloo*
C-13
2,821
Monroe
Toledo*
H-10
905
Cumberland
Watseka*
J-5
4,235
Iroquois
Yorkville*
G-3
632
Kendall
' County Seat
58
LAKE. COOK.
AND DU PAGE
COUNTIES
® EVANSTON
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Park Forest • S. ChicaBO His.
MADISON AND
SAINT CLAIR
COUNTIES
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URBAN POPULATION ^.h" °'
AND LOCATION "-^,
Incorporated Cities and ™' mo,™.
Towns with Populations | *
of 1,000 or More p„, J„';
U. S. Census, 1950 „. E. Molins
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