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Full text of "Man's effect on the fish and wildlife of the Illinois River"

' L I B R A FL Y 

OF THE 
UNIVERSITY 
or ILLINOIS 



cop .2 



"MUHAL HISTORY 
SURVEY 



V'. 




MAN'S 

EFFECT 

ON THE FISH 

AND WILDLIFE 

OF THE ILLINOIS 

RIVER 



inois 

Natural History Survey 
Biological Notes No. 57 
Urbana, Illinois 
June, 1966 



f^ATUHAi 



mio,]f 



JU/^ .-: 






Harlow B. Mills, William C. Starrett, and Frank C. Bellrose 



TE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION NATURAL HISTORY SURVEY DIVISION 



Fig. 1. — Illinois Ri\< r and its drainam' basin, indicating 
thr main features discussed in the text. Approximate limits 
of the drainage basin arc indicated by the heavy broken lines. 




LAKE 
MICHIGAN 



CHICAGO 



COVER PHOTO: Natural History Survey crew taking dissolved oxygen readings with a galvanic oxygen analyzer. Photo 
by George W. Bennett. 



I 



MAN'S EFFECT ON THE FISH AND WILDLIFE 
OF THE ILLINOIS RIVER 

Harlow B. Mills, William C. Sfarrett, and Frank C. Bellrose 



THIS IS A DOCUMENTED REPORT on changes 
in the Illinois Ri\er, primarily in the past 75 years, 
with emphasis on the biological modifications which have 
occurred and are occurring as a result of man's activities. 

The Illinois Ri\er has been called the "most studied"' 
ri\er in the world. Certainly there is a great heritage of 
biological information obtained from this stream. We 
have drawn freely on the observations of Kofoid, Forbes, 
Richardson, and many others, and have included more 
modern observations which we and some others have 
been in a position to make. 

The river has not shown steady changes from year to 
year. Rather, many of them have occurred with great 
rapidity and some have not been permanent. For ex- 
ample, the acreage of water, which went up greatly due 
ic) di\ersion from Lake Michigan in 1900, was reduced 
almost to its pre- 1900 surface by 1913. This reduction 
was due to the development of levee districts, which 
claimed and drained large areas of the floodplain, and 
subsequently to decreased lake water diversion in the 
19.30's. 

Most of the observations in this publication relate lo 
the main stream and its lateral bottomland lakes, t)ul 
these areas are only what the basin makes them. 

THE RIVER AND ITS BASIN 

Till' basin of the Illinois River and its ti ibutarii'S is 
comprised of 32,081 scpiare miles, which is more than 
half the area of the state of Illinois (Bariows 1910: 1). 
The name "Illinois" is applied to that part of the chain- 
age below the confluence of the Kankakee and Dcs 
Plaines rivers southwest of Chicago, the Kankakee 
rising in Indiana and the Des Plaines in Wisconsin. The 
group of glacial lakes in the northeast part of the state 
drains into the Illinois River through the Fox Ri\cr. 
The Illinois River is 272.4 miles long, and ilii- cniirc 
waterway from Lake Michigan lo the mouth of ihc 
river is 327 miles long. 1 he livcr flows nearly west lo 
Hennepin where it turns abiuplly southwest, arriving 
at the Mississippi near Grafton, above St. Louis (Fig. 1 ). 
Thus, it traverses a large section of l\ni slate, and is 
affected by and affects the majority of the stale's citizens. 

Barrows (op. cit.) referred to the Illinois valley as 
the most conspicuous topographic feature of Illinois. Ilr 
stated that, ". . . certain peculiarities of ihc lower Illinois 

This j)apc'r is puhlishrct by aulhorily i>f the Stale of IltiiiiiiH. IR.S CM, 
127, Far. .iH.Ili. It is a ( ntitriliutioii frtiiii tlie SectioiiN of A(|ii.'itir ftinltii^y 
and Wildlife Kpsrarrli of the Illinois .Natural History .Survey. Dr. Harlow 
B_. Mills is Clhief of the Survey. Dr. William C. Starrell i.s an At|iia(ir 
Biologist, and Frank C. Bellrose is a Wildlife Spcrialist. 



render it unic|ue among rivers, the region is one of par- 
ticular interest. . . . The lower Illinois presents a second 
peculiarity in its remarkably gentle fall. . . . The average 
fall between Hennepin and Pekin, a distance of .5.'). 8 
miles, is 0.82 inch per mile. The Illinois is a river of 
relatively insignificant volume. Its natural low-water dis- 
charge is less than that of the Rock River and but a 
small fraction of that of the upper Mississippi and Ohio 
rivers. The nearly level channel and the small volume 
result in a very sluggish river, which has bei'n described 
as a stream that 'more nearly resembles the Great Lakes 
than an ordinary river,' and again as one that 'partakes 
more of the nature of an estuary than of a river.' It is 
wholly unecjual to the task of washing forward the sedi- 
ment delivered by its headwaters and its numerous 
tributaries. . . . The average fall of the lower Illinois is 
less tlian that of the Mississippi below the mouth of the 
Illinois. This is tin- reverse of the normal relation be- 
tween tributaries and their main streams." 

This unique condition for a river has been brought 
about by the present stream flowing through much of 
its lenglh in a valley developed in the late Pleistocene 
epoch. During that lime a much larger water volume 
produced by receding glacicis fashionetl llie present 
physiogiaphy. 

It might be well lu-ic lo describe the Illinois Ri\fr's 
bottomland lakes (lateral levee lakes). The river, flow- 
ing in its uimsually wide valley and carrying a silt load, 
drops more of this silt at the quieter edges than in the 
more rapid stream center. This builds u]3 low natural 
levees along ils shores. Overflow of ihe river at high 
water leaves large impoundments behind these levees 
as the water recedes. Usually these impoundments are 
shallowly connected with the river al iheir upper anil 
lower ends. 

Man's trealnienl of the i i\cr has tended lo aggravate 
ils natural tendency to deposit sediment. The building 
of several dams across the river for navigation purposes 
iias lendfd lo slow the water even more. Also, the greater 
tillage (if the agi icultural ujjland has increased the 
amount of sill that is carried into the quiet mainstream 
waters. 

The Illinois River was the highway for exploreis of 
the area, and early settlements were made on its shores. 
Many early writers were impressed by it. 

Following an ascent of the Illinois River in 1673, 
Marquette (Kenton 192.5) wrote as follows: "We lia\e 
seen nothing like this river that we enter, as regards to 
its fertility of soil, its prairies and woods; ils cattle, elk, 
deer, wildcats, bustards, swans, ducks, parroquets, and 



even beaver. There are many small lakes and rivers. 
That on which we sailed is wide, deep, and still, for 
65 leagues." 

Thomas Jefferson (1787:13) wrote "The Illinois is 
a fine river, clear, gentle, and without rapids; insomuch 
that it is navigable for batteaux to its source." In 1838 
Captain Howard Stansbury described the valley as "one 
to five miles wide, deeply overflowed in every freshet. 
filled with bayous, ponds, and swamps, and infested with 
wild beasts . . ." (Mulvihill and Cornish 1929:27). 

To come down to the beginning of the present 
century, Kofoid (1903:151-155) described the river 
and its bottomland lakes at a high water stage in May, 
as it was just above Havana: "As we leave the sandy 
shore of Quiver we traverse the clear, cold, and spring- 
fed water along the eastern bank with its rapidly grow- 
ing carpet of Ceratophyllum [coontail], and in a few rods 
note the increasing turbidity, rising temperature, and 
richer plankton of the water which has moved down from 
the more or less open and slightly submerged bottom 
to the north. . . . The water [of the river] also appears 
much more turbid by reason of silt and plankton, and no 
trace of vegetation is to be seen save occasional masses 
of floating Ceratophyllum or isolated plants of Lcmna, 
Wolffia, or Spirodda [duckweeds]. ... As we plunge 
into the willow thicket on the western shore we have to 
pick our way through the accumulated drift lodged in 
the shoals or caught by the trunks of the trees or the 
submerged underbrush. . . . From this dark labyrinth we 
emerge to the muddy but cjuiet waters of Seeb's Lake 
with its treacherous bottom of soft black ooze. We next 
enter a wider stretch of more open territory with scat- 
teied willows and maples and a rank growth of semi- 
aquatic vegetation, principally Polygonums [smartweeds]. 
The water is clearer and of a brownish tinge (from the 
diatoms) , while mats of algae adhere to the leaves and 
stems of the emerging plants. A flock of startled water- 
fowl leave their feeding grounds as we pass into the wide 
expanse of Flag Lake. We push our way through lily 
pads and beds of lotus, past the submerged domes of 
muskral houses built of last year's rushes, and thread 
our way, through devious channels, among the fresh 
green flags and rushes [probably river bulrush, Scirpii.i 
fimnatilis] just emerging from the water. Open patches 
of water here and there mark the areas occupied by 
the 'moss' or Ceratophyllum, as yet at some depth below 
ihc surface. The Lcmnaccae [duckweeds] are every- 
whiic li>(li;(d in mats and windrows, and amidst their 
green, one occasionally catches sight of a bright cluster 
of Azolla [moscjuito fern]. The water is clear and brown- 
ish save where our movements stir the treacherous and 
mobile bottom. . . . Thompson's Lake, the largest ex- 
panse of water in the neighborhood, is wont to be rough 
in windy weather, but if the day be still we can see the 
ricli aquatic vegetation which fringes its margin and lies 
in scattered masses toward its southern end. Its waters 
seem somewhat turbid, but more from pl.mklon lli.ui 



from silt, though the deep soft mud which forms much 
of its bottom is easily stirred. . . . The new vegetation 
is already springing from the decaying and matted stems 
of the preceding summer." 

Later in the season when the water was at a low- 
stage, Kofoid (op. cit.:155) noted, "The backwaters 
have been reduced to the lakes, sloughs, bayous, and 
marshes which abound everywhere in the bottom-lands."' 
Flag Lake had lost its connection to the river and was 
a "sea of rushes." Thompson Lake still maintained a 
connection of sorts with the Illinois through a slough, 
and was choked with vegetation at its southern end. 
Quiver Lake was completely choked with aquatics ex- 
cept for one narrow channel where clear, ojjen water 
prevailed. 

The present-day condition is well described by Star- 
rett and Fritz (1965:88) : "Today Quiver Lake is de- 
void of aquatic plants. The formerly deep basin of the 
lake has been filled in with 4- to 8-foot deposits of 
silt. Turbid water at depths of over 3 feet and a soft. 
flocculent bottom prevent the establishment of aquatic 
plants in the lake. Conditions in Quiver Lake are dupli- 
cated in many of the other floodplain lakes of the Illinois 
River: that is, in the past 35 years siltation has greatly 
changed the ecology of these lakes." 

HUMAN POPULATIONS AND ACTIVITIES 

In the early days of exploration and settlement of 
Illinois the rivers were the arteries of travel, communica- 
tion, and commerce. It was not until the era of rail- 
roads that the people of Illinois were in a great measure 
emancipated from the rivers. 

Little concern was shown about changes in. or the 
changing of, the Illinois River for the first 250 years of 
its use by white people. Its character seemed to remain 
about the same, although the greatest flood ever re- 
corded for the river was in the 1840's. Steamboats made 
their way far up its reaches in the 19th centuiy. Cities 
sprang up along its shores and. near the headwaters. 
Chicago began its growth. Events happened rapidly 
from the last ciuarter of the 19lh centuiy to tiie present 
time. 

To gi\e a simple illustration of the development in 
(lie river's basin, the population of the counties which 
are all or in part drained by the Illinois River changed 
from about a half-million in 1850 to 1.629.738 in 1870. 
Hv 1964 this figure had risen to 8.537.900 of a total state 
population of 10.500.000. 

Man has made several major changes in the river 
itself. On January 1. 1900. the Sanitary and Ship Canal 
was opened at Chicago, connecting the Des Plaines and 
Illinois rivers with Lake Michigan. The great quantities 
of water thus diverted flushed untreated domestic sew- 
;ige and industrial wastes down the canal and into the 
Illinois River system. This directed these materials 
away from the lake, which the city used as a source for 
its water supply. 



Forbes & Richardson (1919:140-141) reported an 
average rise of 2.8 feet at Havana as a result of this 
diversion, and between Juno and September the level 
rose an average of ;?.6 feet abo\e piediversion averages. 
This flooding had several effects on the river. It penna- 
ncntly inundated tliousands of acres, ultimately kilting 
bottomland forests. Where trees like the pin oak 
[Qucnus lialtistiis) and the pecan (Carya illinocnsi\) 
were in\()l\ed, this meant a loss of food for mallards 
and wood ducks, but tiiere was also a considerable in- 
crease in water surface whicli was beneficial to the fish- 
ery. Forbes and Richaidson (op. cit.:141) conunenlcd 
that Thompson Lake increased in surface from 1,94;5 lo 
5,072 acres. As late as 1940, dead snags from this 
"drowned forest" were still in evidence, hut time and 
man's later activities have erased most of the traces of 
the old lakes, sloughs, and bottomland forests which 
existed prior to the 1900 diversion. 

These same authors (op. cit.:142) give a good ac- 
count of the effects of this inundation : "This destruc- 
tion of inshore and alongshore vegetation has been 
especially conspicuous in the broad belt of deadened 
trees and shrubs along the banks, especially in the middle 
course of the stream from Peoria southward. Otiier im- 
portant effects arc beginning to appear as these dead 
trees weaken and fall into the water of the stagnant 
lakes, fouling them, in the hottest weather, with the 
products of vegetable decay." 

In 1848 the Illinois-Michigan Canal was opened, 
and in 1907 the Henne]3in Canal connected the Illinois 
with the Mississipjji. Drainage of bottomlands for agri- 
cultural purposes followed closely on the heels of the di- 
version from Lake Michigan. Actually drainage started 
in a small way prior to 1900 (Mulvihill and Cornish 
1929:38), but most of the drainage enterprises were ini- 
tiated between 1903 and 1920. The last levees were 
started between 1918 and 1921. Initially there were 
400,000 acres subject to overflow between La Salle and 
Grafton. At the height of the drainage period iheic 
were 38 drainage districts and three private drainage 
areas aggregating 200,000 acres. Spring and Thompson 
Lakes, long known for their fisheries and their concen- 
trations of waterfowl, were eliminated as were a host 
of smaller lakes and sloughs. How drainage and levees 
have changed the floodplain near Havana is illustrated 
by Fig. 2. 

There has been some aliandoiunent of drainage 
districts. Prior to 1920 the Partridge District, across 
from Chillicothe, failed, and after the Hood of 1926 
the Chaulauc|ua Levee District near Ha\ana and llie 
Hig Praiiie Levee District near Heardslown were discon- 
tinued. These abandonments resulted in a return of 
8.000 acres to fish and wildlife habitat. 

Another human activity has conspicuously changed 
the river. Hefore 1900, low dams were buill at Mar- 
seilles, Henry, Copperas Creek, La Grange, and Kamps- 
ville. Because they were low, their greatest effect on the 



stream was during periods of low water. During the 
1930's. higher navigation dams were built at Dresden 
Heights (22 ft ) , Marseilles ( 24 ft) , Starved Rock ( 19 ft j , 
Peoria (11 ft), and La Grange (10 ft). Moreover, a 
navigation dam on the Mississippi at Alton raised water 
levels in the Illinois River as far north as Hardin. 

Barge traffic on the ri\er is now very heavy, and 
there is a conseciuent effect on the turbidity of the water 
in the main stream and adjacent waters. 

Soil pollution has been present in Illinois River 
waters since the recession of the last ice sheet. However, 
the laying bare of the soil in agricultural operations has 
greatly increased the problem. 

A study of Lake Decatur, on the Sangamon River, 
a tributary of the Illinois, showed that the rate of sedi- 
mentation was about 20 percent greater in the decade 
starting in 1936 than it was in the preceding 14.2 years 
(Brown, Stall, & DeTurk 1947). In one county above 
the impoundment row crops increased from 39 percent 
of the total area in 1924 to 64.5 percent in 1943. There 
is a probable cause-and-efTect relationship here. This 
sedimentation is a serious matter to organisms that live 
in the water as well as to those that use it. Further, it 
displaces water. Where waters are stilled, the load of 
silt is dropped, and the water is replaced by .soil. 

In 1964, in the counties drained wholly or in part 
by the Illinois River 6,220,200 acres were planted to 
corn for grain which was valued at .$530,288,900. and 
an additional 3,466,100 acres were planted to .soybeans 
(Illinois Cooperative Crop Reporting Service 1965). 
Thus, in these counties 47 percent of the land surface 
in 1964 was in row crops which leave the soil vulnerable 
to erosion. 

The streams thai flow into the Illinois have a steeper 
gradient than dfH-s the Illinois in its central and lower 
reaches. Since the ri\er is impounded and the gradient 
is low, it has difficulty carrying its silt load. Therefore 
a tremendous amount of this turbid burden is deposited 
in the remaining floodplain lakes when spring flood- 
waters top the low natural banks. An example of the 
seriousness of siltation is evident in the study made In- 
stall & Melsted (1951) of Lake Chautaucjua, They 
found that in a 23.8-year period the sediment had 
reduced the storage capacity of this artificial lateral 
bottomland lake by 18.3 jjercent. nearly one fifth. Other 
bottomland lakes are steadily diminishing in size and 
depth as sediments continue to be deposited in spite of 
soil conservation measures. 

The basic reason for the 1900 diveision of Lake 
Micliigan water into the Illinois waterway was to dilute 
sewage and transjjort it away from Chicago. Since that 
time the treatment of sewage in the Chicago area has 
been greatly impro\ed, but the rich effluent still affects 
the waters of the waterway b(4ow the city (Keup. In- 
gram, Geckler, & Homing 1965). Moreover, the other 
cities within the Illinois River basin have grown, and 
make their increasing demands on and contributions to 
the stream. 








b) — 1960 



Fig. 2. — Illinois Rivci liottoiu near Havana, Illinois, a) as it was prior to lOl'J, and hi as it was in 1960. (From Starrrtt ..'< 
Fritz, 1965.) 



Domestic sewage and industrial wastes are not the 
only source of organic ]jollution of our streams. With 
the development of larger and larger cities, the paving 
of more streets, parking areas, etc., the storm water 
runofT adds a considerable amount of organic matciial. 
A study by Wcibel, Anderson. & Woodward (1964) of 
a sewered storm water runofT from a 27-acre, residential- 
light commercial area in Cincinnati, Oiiio, disclosed that, 
assuming a secondary sewage treatment plant effluent 
at the population density and environmental conditions 
of this area, the o.xygcn demand of the storm water 
would equal about 60 percent of the oxygen demand of 
the sewage effluent on a yearly basis. 

Man is contributing other things to the Illinois 
River. No one knows what all of these contributions 
are, in addition to those from industry and farming op- 
erations, or what they do to the environment. Usually 
these additions come to the attention of biologists only 
when there is a conspicuous deterioration of the biolog)' 
of a stream. 

Occasional accidents occiu" which affect the biology 
of the ri\er, as, for example, when large quantities of 
ammonia fertilizer inadvertently escaped into it below 
Peoria in 1961. 

With all that we are adding to the Illinois River, tin- 
known and the unknown, it is certain that the river is 
changing, and in some cases it is deteriorating rapidly 
insofar as it affects the well-being of the animals and 
plants that are dependent on it. 

The following pages include a summary of some of 
our observations on this important stream. While we 
discuss some chemical and physical parameters to this 
problem, we are basically interested in them as they 
affect the fish and wildlife. It is probable that a greater 
future emphasis on the biology of streams will be a 
necessity in any intelligent water management program. 
Without in any way detracting from the importance of 
other fields of specialization, we believe that water biol- 
ogy stands at the center of any water quality consider- 
ation. In the words of Hynes (1961), "Pollution is. 
after all. primarily a biological phenomenon, as the 
things we need to know about water are almost all con- 
cerned with living organisms. Can we or our animals 
drink it? Will it be a good medium for brewer's yeasts? 
Is it likely to carry disease? Will it smell nasty as the 
result of biological degradation of organic matter? Can 
fish live in it?" 

TURBIDITY 

As mentioned previously, the Illinois River was at 
one time characterized as being clear. It has always 
carried some silt load, of course, but prior to human 
settlement of the basin this must surely iiave been a 
nominal one, and doubtless was most obvious during 
periods of high water. When the while settlers estab- 
lished the intense agrarian culture in the area, their 
plows and axes began a change in the river which still 



goes on. Kofoid (1903:179) discussed the matter of 
clarity as it was in 1896. He measured clarity by sub- 
mciging a white plate of scmiporcelain. The depth at 
which this plate disappeared from view was measured 
in centimeters. 

"As might be expected in the river environment," he 
stated, "when floods occur the tmbidity is often extreme, 
and is exceedingly variable according to the locality and 
the river levels. The extreme range of our records 
extends from 1.3 cm. ['A inch], in a Spoon River flood, 
to 260 cm. [8'/? feet], in Quiver Lake, under the ice. 

"In the [Illinois] river the great majority, about two 
thirds, of the records lie between 20 and 50 cm. [8-20 
inches], while the extreme range is from 2 cm. [% inch], 
in the flood of May 1897, to 1 15 cm. [45 inches], in the 
declining waters of July, 1896." The range for two-thirds 
of his readings would be roughly estimated to equal 
25-103 turbidity units (Jackson 1954:39). 

Recent turbidity measurements have revealed how 
much greater the silt load is in the waters of the ri\er 
than it was about 70 years ago. In 1963 and 1964, 
during periods of minimum flow when the silt load 
would be lowest, the turbidity was determined to be 
from 79 to 220 units in the La Grange Pool. Thus at 
this low-river stage, the modern measurements were 
at the lowest reading three times those of Kofoid's and 
at the highest reading over twice the 1896 (igme. We 
have already discussed in general terms what this silt 
load is doing to water impoundments, and its relation- 
ship to modern agriculture. The lower and middle 
stretches of the river tend to be kept in a more turbid 
condition because of the movement of tow boats up and 
down the main stream (Starrett, unpublished). Tin- 
increased turbidity of the Illinois River has come from 
the greater exposure of the soil to precipitation and 
resulting erosion, as discussed in the previous section, 
and from the hastening of the How of the nmddy wateis 
into the stream. Great marshes, for example, used to 
impede the movement of rainfall to the ri\er. hut these 
marshes are largely gone now. 

That the silt load in the lower river tends to be 
greater than in the upper stretches is indicated in the 
following tabulation which lists the turbidity units by 
navigation pools, beginning with the Alton Pool at the 
river's mouth and ending with the Dresden Pool in the 
Des Plaines River just below Chicago. 

Narigalion Raii^r in 

Pool Turbidily Units 

Alton 71-320 

La Grange 79-220 

Peoria 15-140 

Star\-cd Rock 1,5-52 

Marseilles 15-28 

Dnsclcn 15-27 

These readings were made during the periods of min- 
imum flow in the fall months of 196!^ and 1964. During 
j)eriods of high water all of these readings would, of 



L 



I 



course, be much greater; as high as 2,000 lurbidity units 
have been noted by the Illinois Sanitary Water Board 
in the lower river during flood conditions. 

Turbidity in parts of Peoria Lake is sometimes in- 
creased by large populations of minute floating plants 
known as phytoplankton, but in general the river's lack 
of clarity is due to suspended silt. Turbidity probably 
affects the procurement of food by sight-feeding fish 
(Starrett & Fritz 1965). It also affects production of 
plankton, and the well-being of various larger forms 
of aquatic plant and animal life (Ellis 1936). 

DISSOLVED OXYGEN 

Oxygen dissolves in water according to certain phys- 
ical laws, and ac]uatic life has evolved to live and respire 
within the normal limits of this solution. Suffocation 
can take place if waters carry pollutants which will 
oxidize and remove this gas faster than it can be 
replaced. This makes too great a demand on the avail- 
able oxygen, and fish, as well as other forms of ac]uatic 
life, will die. 

The requirements for oxygen on the part of different 
aquatic species arc not the same. Trout, for example, 
require more dissolved oxygen than do carp or goldfish. 
It appears from Ellis's stu'dies (1937:372-37.3) that 5 
parts per million (ppm) of dissolved oxygen is the lower 
limit for maintaining a desirable fish fauna in a river. 
Tarzwell (1958:19) believed that ". . . for a well- 
rounded warm water fish population, dissolved oxygen 
concentrations must not be below 5 p. p.m. for more 
than 8 hours of any 24-hour period and at no time 
should they be below 3 p. p.m." Diu'ing the winter 
months on the Illinois River, Thompson (1925:431) 
noted that carp and buffalo were found in water having 
as little as 2.5 ppm of oxygen, but a variety of fish was 
found where there were 4 ppm, or more, and the greatest 
variety was found where there were 9 ppm. We also 
have foimd fish living in water with below 3 ppm of 
oxygen ; however, we believe that prolonged low oxygen 
conditions are having a drastic effect on acjuatic orga- 
nisms in the river. 

Continuous low oxygen determinations indicate that 
pollutants carried by the stream have a high biological 
and chemical demand on the oxygen supply and that the 
stream is in poor condition for fish life. Because the 
quantity of dissolved oxygen in tlie Illinois River water 
becomes an important limiting factor and has a strong 
relationship to the health of the organisms living in that 
water, it is important that we briefly review this factor. 
That low dissolved oxygen is a present as well as a 
past problem is indicated bv the readings presented in 
Table 1. 

Prior to 1800 the entire Illinois River syslcTu wilhoul 
doubt carried enough oxygen to support a well-diversi- 
fied, healthy, fish population. Possibly a turning point 
occurred when the flow of the Illinois and Midiigan 
Canal was reversed and began to biing sewage from 



Chicago to a point in the river at La Salle in 1871. The 
Peoria-Pekin area also began to develop along the 
middle stretch of the river. Sewage and industrial wastes 
coming into the river were untreated. 

Kofoid (1903:199) estimated that the Illinois River 
received the untreated waste from a population of 
1,032.229 people in 1890. There were no statistics as 
to the gallonage that this represented, but considering 
the pumpage into the water systems of the cities as an 
approximation of the sewage flow, he calculated that in 
1897 the flow was 540.529,061 gallons per day. Kofoid 
stated (loc. cit.:230) that before the Sanitary and Ship 
Canal was opened in 1900 the nitrogenous material in 
the Chicago sewage was in the process of rapid oxidation 
in the upper reaches of the Illinois and Michigan Canal 
near Lockport, and that the process was largely com- 
pleted by the time the canal water reached the Illinois 
River. He also said that in the summer months the 
wastes from Peoria were well decayed before reaching 
Havana, although in the winter the sewage was not so 
well oxidized. 

As mentioned earlier, the opening of the Sanitarv 
and Ship Canal in 1900 brought into the Illinois great 
quantities of sewage-laden lake water. Forbes & Richard- 
son (1919:139) mentioned that in 1913 the flow of the 
Sanitai-y and Ship Canal amounted to 85.7 percent of 
the flow of the original river at Peoria. 

By 1911 the upper part of the river was heavilv 
polluted. Forbes (1911:5-6) stated: "Immediately 
below the mouth of the canal we have in the Des Plaines 
a mingling of these waters, and the Illinois River itself, 
below the jimction of the Des Plaines and the Kankakee, 
the septic contributions of the former stream are largelv 
diluted by the comparatively clean waters of the latter. 
Nevertheless, we had in July and .■\ugust what mav be 
called se]3tic conditions for twenty-si.x miles of the course 
of the Illinois from its origin to the Marseilles dam. At 
Morris, which is on the middle part of this section, the 
water, July 15, was grayish and sloppy, with foul, pri\y 
odors distinguishable in hot weather. . . . Putrescent 
masses of soft, grayish or blackish, slimy matter, loosely 
held together by threads of fungi and densely covered 
with bell animalcules, were floating down the stream ; 
and chunks of this material, from the size of a walnut 
to that of a milk pan, occasionally rose to the surface, 
c\idently borne up by the gasses developing beneatii 
them." He found that at that time the dissolved oxygen 
at Morris was only 9.8 percent of satination. Sixteen 
miles below Morris, at Marseilles, the oxygen was onlv 
7.5 percent of saturation. However, in the unpolluted 
Kankakee River 9 miles above Morris the dissolved 
oxygen was 1 12 percent of satination. 

The oxygen determinations gi\en in Table 1 show 
how polluted the Illinois River was in 1911 and 1912 
from Morris to Peoria. 

Clonditions became men worse during and imme- 
dintelv following World W.n 1. Purdy (1930:2), who 



8 



Table 1. — Summary of minimum dissolved oxygen determinations near surface in channel of the Illinois and Des Plaines rivers 
during summer months of 1911, 1912, 1922, 1923, 1925, 1926, 1928, 1950, 1964, and 1965. 



Nearest 
Town 



Dissolved Oxygen in Parts per Million 



1911» 



1912" 



1922'' 



1923« 



1925'' 



1926'' 



1928'' 



1950" 



1964' 



1965' 



Lockport ... 0.01 

Channahon ... 0.2 

Morris 0.9 ... 0.2 

Marseilles 0.5 ... 0.1 

Ottawa ... 0.3 

La .Salle ... 0.5 0.0 0.0 

Peru 2.7 ... 1.7 

Spring Valley 2.0 ... 0.0 0.3 

Hennepin 2.2 1.8 ... 0.0 0.1 

Henry 2.1 1.0 0.4 0.0 

Lacon 2.1 ... 0.8 0.4 

Chillicothe 2.3 2.7 0.4 0.0 0.3 

Rome 1.9 ... 0.0 0,2 

Narrows (Peoria) 4.3 5.7 2.6 3.0 

Pekin 5.4 5.2 3.3 2.2 

Kingston Mines 4.1 6.6 3.0 5.5 

Havana 3.6 ... 1.3 3.8 

Browning 3.7 . ... 3.9 

Bcardstown 4.8 2 7* 2.3 2.7 



0.3 
1.2 



0.5 



0.4 
0.4 
0,1 
0.0 
2.4 



0.6 



0.1 

0.2 

0.1 
0.0 
0.5 



2,4 



2.9 



5.3 

3.9 
2.9 
3.9 



4.9 
3.5 
2.9 
5.1 
4.8 
5.0 



2.3 
2.3 



1.6 
4.1 
2.5 
2.8 
5.1 
4.9 
5.1 
3.8 
3.0 
2.7 



1.0" 



" Barlow (1913:40-45). 

'' Hoskim. Ruchhoft, & Williams (1927:114-122) Lowest of monthly mean determinations for Julv and .August 1922. 

■■ Greenfield (192.';:26-27 and 3(1-31). 

•> BorufT & Buswell ( 1929:57-1U8) . 

*■ Mondala. Chairman (Report of the Illinois River Pollution Commission. 195I:LA 41 Table I .-Xnalytiral Data of Illinois Sanitary Water Board). 

t Starrelt (Illinois Natural History Survey data). 

^' Mr. Ralph E\ans of the Illinois Water Survey furnished the data. 

* Samples laiten in 1921 rather than 1922. 



Studied the river in 1921 and 1922, said: "Growth of 
the city of Chicago, with heavy increase in amount of 
sewage and of stockyard waste overburdening the al- 
ready polluted Illinois River, which, with reduced area 
for overflow, limiting levees, and increased volume. 
must therefore flow more rapidly in its narrowicl 
channel, with the result that each succeeding year its 
organic matter is carried fartiier downstream, before 
the offensive organic content is sufficiently removed." 
Richardson believed (1921b: 33) that in the 1915-1920 
period the southward progression of this offensive condi- 
tion in the Illinois Ri\i'r was iiitiviiig at the rate of 16 
miles a year. 

Conditions upstream from Peoiia are niut li (lillnciit 
now from those of about 40 years ago, as a coin|)arison 
of the oxygen determinations made in 1922 and 196.") 
indicates (Table 1). This improvenifut is interesting 
when one considers the gieat growth that has been 
occurring in population and industiy in the Chicago 
metropolitan area. The improvement may ha\e been 
due to several factors, including the construction and 
operation of the tremendous sewage treatment plants 
by the Chicago Sanitary District through a program 
instittited in 1922. and the lock and dam sy.stem l)uill 
in the I93f)'s whidi slowed up the moMiiifiU of the 
water. The adoplicjn of belter water pollution laws by 
the state also had its effect. 

Hoskins, Ruchlujft, & Williams (1927:2,5) stated 
that the total combined domestic and industrial pollu- 
tion cmiJtiicl into ihe Illinois Rivii in 1922 was the 



equivalent of that from 6,211,471 people. Tlie popula- 
tion ec|uivalent of domestic and industrial wastes entering 
the river in 1960 (United States Public Health Service 
1963) had been reduced to 2,417.000, in spite of ex- 
panding human populations and increased industry in 
the basin. This change reflects the great progress which 
has been made in the treatment of wastes and indicates 
the magnitude of work yet to be done. 

In spite of the dramatic improvement described 
above, our oxygen analyses made in 1964 and 1965 
(Fig. 3) indicated that most of the river had less than 
5 ppm dissolved oxygen. We consider the determinations 
for the na\ igation pools to be (luite typical for nK)ining 
samples during warm weathei. I he downward slopes 
of the oxygon graphs below the clams (Fig. 3) are 
similar for all pools but Starved Rock, which is affected 
on the right bank by effluents from Marseilles and the 
Fox River. The higher oxygen readings just below the 
dams, and the declining curves as one proceeds down- 
stream from each dam, indicate that additional oxygen 
is added as the water |jasses over and tluough the dams 
and locks, and that this is rapidly removed by the high 
demand for the oxygen caused by the pollutants. Hartow^ 
(1913:36) noted a similar increase in oxvgen in the 
river below the Marseilles Dam in 1912. 

The similarity of the declines in oxygen below the 
dams after the initial upsurge indicates that there arc 
still high biological and chemical tiemands for the dis- 
solved oxygen, and the amount available is at about a 
breaking point insofar as fish life is concerned. 




■"4.5 

z 

UJ4.0 
O 

X3.5 
O 

3.0 
a 

in 

o 1.5 



■STARVED ROCK 

1 t:0CK a DA M :■!! ■•■ 

STARVED ROCK POOL 
30 JULY 1965 
0725 to 10*3 CST 
TEMP 26 4 to 290"C. 



.-V ,— ' 



UiR5£ILLES POOL 
^9 JULf ,965 
0650 10 1122 CST 
TEMP 29 5° to 302° C, 



196! 



DRESDEN POOL 



0835 10 1035 CST 
TEMP 302* 10 32i"C. 



V\ 



\.' 



230 234 238 242 246 250 254 258 262 266 270 274 278 282 286 290 
MILES FROM MISSISSIPPI RIVER 



RIP UF Annw 
LOWER END PEORIA DETWEILLER PEORIA LAKE Ilqugh 

PEORIA LAKE^^ / NARROWS P*"" LIGHT \^CHILLICOTHE__,/ LACON 



LAKE SENACHW1NE 
HENRY ^ HENNEPIN 



VERMILION 
PERU RIVER 

SPRING VALLEY ' LASALLE 



33.0r 



PEORIA POOL . 

6 8 7 AUGUST 1964 I 5 AUGUST 1965 ' 

0528 10 1113 CST 0808 to 0930 CST 

TEMP 27 2° 10 29 7°c1tEMP 25 6" Io 26.8°C. 




186 190 194 198 202 

MILES FROM MISSISSIPPI RIVER 



BEAROSroWN SANGAMON RIVER b„oWNINO 




LIVERPOOL 


MACKINAW 
KINGSTON MINES RIVER 


PCKHI , 


GRANGE H^HHH^^HBJI^^^^^H 
|ldcx q dam -^i^^^^^^^^^^^^^^^^^^H 


i^^mimlliii^g 










L» BRMee POOL 









M, 15, 16 JULY 1964 I 1 1 AUGUST I9G9 
0517 to 1020 CST 0545 to ll56 CST 

TEMP. 23.3° to 26.2° C.I TEMP. 25.0° to 25.7° C 




MILES FROM MrSSISSIPPt RIVER 



MISSISSIPPI RIVER 
GRAFTON 



M0NTE7UMa FLORENCE 



NAPLES MEREOOSIA 



«*» 




g3.0 




o 




§2.0 

o 

(A 





ALTON POOL 
12 AUGUST 1965 
0530 to 1515 CST 
TEMP. 23.9° to 27.1° 



V,= 



32 36 40 44 48 

MILES FROM MISSISSIPPI RIVER 



Fig. 3. — Dissolved oxygen determinations in the Illinois River from Brandon Road Lock and Dam to Grafton. Broken lines 
represent readings taken in the summer of 1965; solid lines represent readings taken in the summer of 1964. (Illinois Natural His- 
tory Survey data.) 



10 






The poor oxygen content in the La Grange Pool in 
the summers of 1964 and 1965 (Fig. 3 and Table 1) 
probably reflects the eflfects of additional wastes coming 
into the river from the Peoria-Pekin area. Conditions 
were particularly bad during the summer of 1965. This 
has been a problem of some duration. Roruff & Buswell 
(1929:54) in reviewing their own and other studies of 
the BOD (biological oxygen demand) of the river prior 
to 1928, stated: "Physical conditions, especially below 
Peoria and Pekin and below this latter city for some 
miles, tend to show each summer season signs of an 
increasing pollution load. The extra load that is being 
added to the river is due to the increased population of 
the Pekin and Peoria districts, as well as to the veiy 
marked increase in industrial wastes." BorufT (1930:5) 
found that the dissolved oxygen content of the water 
below Peoria and Pekin remained at a low level. 

Our present study of the bottom fauna (Starrett & 
Paloumpis, unpublished) and of the fishery indicates 
that some improvement in conditions occurs below the 
mouth of the Sangamon River at Beardstown. The pos- 
sible influence of this tributary at times is clearly shown 



in the cross-section oxygen readings made in 1964 (Fig. 
4). In the entire cross section of the Illinois River at 
Mile 89.3, just above the mouth of the Sangamon, dis- 
solved oxygen was at a value of 2.4 ppm. The cross 
section at Beardstown at Mile 88.6, also shown in Fig. 
4, disclosed a high oxygen content on the left bank below 
the Sangamon's confluence through Muscooten Bay, and 
a low content on the right or opposite side. However, 
our 1965 data do not reflect such beneficial effects from 
the Sangamon River as were noted in 1964. Tiie longi- 
tudinal section (Fig. 4) below the Sangamon's mouth 
shows that the mixing of the high-oxygen Sangamon 
water in 1964 did not reach midstream until about 
Mile 88. 

BOTTOM FAUNA 

The bottom fauna ( benthos j consists of the macro- 
scopic animals which spend all or a part of their lives 
living on or in the bottom sediments. Certain benthic 
organisms, such as insect larvae, fingernail clams, and 
snails, are important food items for larger animals such 
as fish and ducks (Starrett & Paloumpis, unpublished; 



2.4- 



CF?OSS SECTION 



Left MILE 89.3 RigM 

Bonk 1047 CST Bank 



DISSOLVED OXYGEN- ILLINOIS RIVER 

3 FEET BELOW SURFACE 

16 JULY 1964 



9,0 

80- 

7,0- 

6.0 

5.0 

4.0 

3.0- 



2.0 



6.0 



5.0- 



4.0- 



3.0- 



2.0- 



CROSS SECTION 




HIGHWAY 
BRIDGE 



Left MILE 88.6 RigM 
B(»ik 1000 CST Bonk 




MILE 89 3 



RAILROAD 
BRIDGE 

ILLINOIS 
RIVER 



BEARDSTOWN 



88.0 



LONGITUDINAL SECTION 
BELOW MOUTH OF SANGAMON RIVER 



87.0 




Fig. 4. — A continuous 
scries of dissolved oxygen read- 
ings made in the Illinois River 
with a galvanic oxygen ana- 
lyzer near the mouth of the 
Sangamon River. The graphs 
reflect the increase and mixing 
of dissolved oxygen in the Illi- 
nois River resulting from the 
effects of a major tributary 
having a higher dissolved oxy- 
gen content. Cross section at 
Mile 89.3 is above the mouth 
of the Sangamon River, and 
cross section at Mile 88.6 is 
below. ( Illinois Natural His- 
tory Survey data.) 



MILES FROM 



RIVER 



11 



Anderson 1959:338-339). Much of the Illinois River 
(as well as its adjoining bottomland lakes) is now char- 
acterized by populations of pollution worms of the 
family Tubificidae. However, some of the original di- 
versity of benliiic organisms, such as immature insects, 
clams, snails, leeches, moss animals, and the like, does 
exist in some parts of the river and its lakes. 

Reduction in the abundance of the clean-water ani- 
mals would be expected to have an adverse effect on 
animals which rely on them for food, and, as we shall 
see later, this undoubtedly has happened. 

Changes which have occurred since 1913 in the zones 
of pollution based on the bottom fauna are shown (Fig. 
5). The chart shows that approximately half of the 
river in the La Salle-to-Beardstown section in the 1913- 
1915 period contained principally clean- water benthic 
forms, whereas in the 1964-1965 period most of the or- 
ganisms in the same section of the river were pollution 
worms, which are poor food for fish and ducks. 

Fingernail clams (Sphaeriidae) occurred in large 
numbers in the Illinois River and some of its bottomland 
lakes up to 1954 (Paloumpis & Starrett 1960:423-425, 
and unpublished). The cause for the virtual dis- 
appearance of these important food items is not 
known, but there are strong indications that it was 
a pollution complex of some kind. These tiny clams 
(Fig. 6) still occurred in ihe river below the mouth of 



the Sangamon at Beardstown in 1964 (Starrett & 
Paloumpis, unpublished). 

Snails of the genera Campeloma and Pleurocera also 
occur at the present time in greater abundance in the 
lower river than elsewhere, but we collected a few living 
specimens (Campeloma) in 1964 from the river channel 
below Henry by means of an otter trawl. In Quiver 
Lake, above Havana. Paloumpis & Starrett (1960:425) 
found that a small snail (Cincinttali tmarginata) disap- 
peared simultaneously witii the fingernail clam. In the 
lower part of this lake, which is properly a part of the 
river, all species of snails decreased from 10.76 grams 
per square foot (exclusive of shells) in 1952 to 6.07 
grams per scjuare foot in 1954. and none in 1964 (Star- 
rett & Paloumpis, unpublished) . 

Starrett & Paloumpis did not take midge larvae 
abundantly anywhere in the river in 1964 and 1965. At 
times they were more abundant in fish stomachs than 
in the benthic collections, especially in the Peoria Pool. 
It is possible that seasonal variations and local concen- 
trations of larvae may have accounted to some extent 
for this disparity. 

Burrowing mayflies (Hcxagciiia) were considered 
by Richardson ( 1928) to be clean-water organisms in the 
Illinois River. According to Hunt (1953:55) nymphs 
of Hcxancnia limhata were unable to withstand stagnant 
conditions when tlie dissolved oxygen dropped below 1 



Fig. 5. — Historical rhango in 
pollution of the Illinois River as 
indicated by bottom fauna sam- 
ples. (From Riehardson, 191iH, 
and Starrett & Paloumpis, un- 
published.) 



MILES BELOW 
LAKE 

LOCATION MICHIGAN 
LA SALLE 101.5 

SPRING VALLEY 108.6 



CHILLICOTHE 146.5 

SPRING BAY 154.0 

NARROWS 

PEORIA NARROWS 161.0 



HAVANA 



BEARDSTOWN 



207.0 



238.0 



1913 -1915* 



EARLY 

POLLUTIONAL 



EARLY POLLUTION- 
AL TO EARLY 
SUB-POLLUTIONAL 
IN I9II-I9I2 



LATE 
SUB-POLLUTIONAL 



EARLY CLEAN-WATER 
WHEN NOT AFFECTED 
BY LOCAL SEWAGE 



PRINCIPALLY 
CLEAN-WATER 



CLEAN-WATER 



I 



RATING OF TERMS FROM MOST TO 

EARLY POLLUTIONAL 
LATE POLLUTIONAL 
EARLY SUB-POLLUTIONAL 
LATE SUB-POLLUTIONAL 
EARLY CLEAN-WATER 
CLEAN-WATER 



1920-1925* 



PRINCIPALLY EARLY 
SUB-POLLUTIONAL 



EARLY 

POLLUTIONAL 



EARLY TO LATE 
POLLUTIONAL 



POLLUTIONAL TO 
EARLY SUB-POLLU- 
TIONAL ABOVE 
COPPERAS CREEK 
0AM, LARGELY EAR- 
LY SIJB- POLLUTION- 
AL BELOW 



PRINCIPALLY LATE 
SUB-POLLUTIONAL, 
1920-1923, SHIFT- 
ING TO EARLY 
CLEAN-WATER AFT- 
ER 1923 



I 



I I 

LEAST POLLUTED. 



1964-1965 



»* 



POLLUTIONAL 
MAINLY TUBIFICID 
WORMS AND 
MIDGE LARVAE 



HEXAGENIA NYMPHSi 
AND SPHAERID 
CLAMS APPEAR 
HERE SAMPLES 
ALSO WITH TUBI- 
FICID WORMS AND 
MIDGE LARVAE 



* FROM RICHARDSON (1928:402) 
**FROM STARRETT AND PALOUMPIS (UNPUBLISHED) 



12 



p 



Fig. 6. — Finger- 
nail clams, important 
food items for some 
fish and birds, have 
virtually disappeared 
from the river above 
Beardstown. 




ppm. In 1913 and 1915 Richardson (1925:381) col- 
lected an occasional Hcxagcnia nymph in middle and 
lower Peoria Lake; after 1915 he did not find any in 
the river above Havana. 

Mayfly emergences can be spectacular when millions 
of these insects are drawn to lights and may concentrate 
in such numbers as to be hazardous to traffic. Such 
emergences have been characteristic of many parts of 
the Illinois River. The last time we observed a large 
emergence at Havana was in 1949. Paloumpis & Starrett 
(1960:419) collected Hexagenia limbata nymphs in the 
1950's at Quiver Lake, and in most summers during the 
early 1950's they saw subimagos at or in the immediate 
vicinity of the lake. Since the late 1950's we have not 
observed any mayfly emergences at the lake and Star- 
rett & Paloumpis (unpublished) did not collect any 
nymphs there in 1964. They collected some Hcxagcnia, 
though, in 1964, in the river below Beardstown and in 
the Alton Pool. 

The predominant organisms in the 1964-1965 bcn- 
ihic sam]3les were jJoUution worms and these were quite 
abundant, even in the samples from below Beardstown 
where both mayfly nymphs and fingernail clams were 
taken (Starrett & Paloumpis, unpublished). In 1915 at 
Lake Matanzas, below Havana. Richardson ( 1921 a: 506- 
507) collected only 4.4 worms \kv sc|uare yard, whereas 
Paloumpis & Starrett (1960:430) in 1953 look 11.007 
per scjuare yard in the same area. 

Such drastic changes in the bcnlhic populations as 
those described above can be accounted for only by the 
accunuilative effect of pollution in the bottom muds of 
tlie Illinois River waters. Such changes may not l)c 
shown by chemical analyses. 

AQUATIC VEGETATION 

Within the last 15 years there have been unusual 
changes in the aquatic vegetation of the Illinois River 
and its bottomland lakes. Today there is a vastly dif- 
ferent picture in the vicinity of Havana from thai 



painted by Kofoid at the turn of the century. Flag and 
Thompson lakes disappeared in the early 1920's, the 
result of the building of levees, drainage, and cultivation. 

Kofoid (19():i:236) slated: '"The ac|uatic environ- 
ment at Havana im|}resses the \isiting biologist who for 
the first time traverses its river, lakes, and marshes, as 
one of exceedingly abundant vegelalion. indeed almost 
tropic in its luxuriance. . . . He will find acres upon 
acres of 'moss,' as the fishermen call it — a dense mat of 
mingled Ccratophyllum and Elodca choking many of 
the lakes from shore to shore, and rendering travel by 
boat a tedious and laborious process. . . . The carpels 
of Lcmnaccac will be surprising, and the gigantic growths 
of the semiaquatic Polygonums will furnish evidence of 
the fertility of their environment." 

The first big change in aquatic vegetation came 
shortly after Kofoid had completed his study, with the 
1900 diversion of Lake Michigan waters into the ri\er. 

Richardson (1921b:46) recorded the disappearance 
of aquatic plants from Peoria Lake in 1920 as follows: 
"The luxuriant growths of coarse aquatic plants ( Pola- 
mogeton, Ceratophyllum, Scirpus, Vallisineria, etc.) that 
covered several .square miles of Peoria Lake at mid- 
summer and autumn levels between 1910 and 1914, 
and their rich fauna of small invertebrates along \\ith 
them have disappeared now altogether in the upper and 
middle lake except for an occasional scraggly clump at 
the very edge. In the lower lake, a thin patch of 
Potamogeton and Ccratophyllum, covering less than two 
acres, was still growing in a small springy slough, . . ." 

Thompson (1928:304) reported that pondweeds 
(Potamogctons) and other large aquatic plants in Peoria 
Lake, the river, and connecting sloughs and lakes down- 
stream, disappeared almost completely between 1915 
and 1920. But about 1922 pondweeds began to reap- 
pear and increase rather rajiidly in many areas of Peoria 
Lake. 

Purdy (1930:113) slated that in 1921 Peoria Lake 
held some growths of pondweeds and algae, but these 
were so slight as to be overlooked by the casual obseiA'cr. 

From the late 1930"s to the middle 1950's, in some 
places along the central stretches of river there was an 
abiuulance of aquatic vegetation, but this has now al- 
most completely disappeared. The reasons for this are 
not clearly understood, Thcic may be some inimical 
materials in the waters now, and it appears that the silta- 
tion of the last decade has been a factor. Siltation affects 
aiiuatic jjlants adversely in two ways: it produces a 
tiubidity which reduces the penetration of light and in- 
hibits photosynthesis, and it creates bottom conditions 
which make it difficult or ini]Jossible for various species 
of jilaiits to obtain anchoiage whc-n they are buffeted by 
wave action. 

The importance of wave and fish action in rc- 
suspending sediment particles in Lake Chautau(|ua has 
been jjointed out iiy Jackson & Starrett (1959). Dining 
the spring of 1953 tliey found that, with an increase in 



13 



wind velocity from light to strong, suspended particles 
increased more than fourfold (162 to 700 turbidity 
units) . The actions of bottom-feeding fish also caused 
a resuspension of sediment particles. Because it takes 
from 7 to 12 days for much of this sediment to settle 
from Lake Chautauqua, this lake (as with most such 
lakes in the Illinois River valley) is in a highly turbid 
state most of the time. 

Sago pondweed (Potamogclon pcctinatus) is more 
tolerant of reduced light than most other aquatic plants. 
In spite of this, Bellrose (1941:261-263) found that 
from 1938 to 1940 sago pondweed in Lake Chautauqua 
did not thrive in water more than 48 inches deep, and 
was absent in water more than 56 inches deep. Later, 
at the same lake, Jackson & Starrett (1959:159) re- 
ported that sago pondweed grew best when the maxi- 
mum water depth was about 3 feet. 

Sedimentation of Lake Chautaucjua was accelerated 
by the great spring floods of 1943 and 1944. Beds of 
aquatic plants, which had declined slightly from 1938 
to 1942 (Bellrose 1941:243, and unpublished) were al- 
most wiped out by the high turbid waters of the two 
following flood years. Probably because additional silt 
was deposited as a "false bottom" over the previous 
"firm bottom," aquatic plants never did return to their 
former luxuriance in Lake Chautauqua. For all practi- 
cal purposes, longleaf pondweed (Potamogeton ameri- 
canus), coontail (Ceratophyllum demersum) , and bushy 
pondweed {Naias guadalupensis) were lost as important 
items in the lake's ecology. Sago pondweed is the only 
plant which has been common since the 1943 flood. It 
varies in abundance in Lake Chautauqua annually, de- 
pending on the depth of water in May and June; low 
water during this period has favored a fair growth dur- 
ing some summers. The most extensive recent growth 
occurred with the low, stable water levels of 1956 when 
the beds covered 1,237 acres early in the fall. 

The Peoria Dam, put into operation in December. 
1938, stabilized low water levels in Peoria Lake, and 
coontail, bushy pondweed, and sago and longleaf pond- 
weeds, as well as wild celery (Vallisencria spiralis), in- 
creased greatly in the 1940's, with a peak abundance in 
1949. Early in the autumn of that year aquatic plant 
beds were lush, covering several thousand acres of this 
10,000-acre lake. After 1949 these beds declined in 
vigor and abundance until, following a small gain in 
1952 and 1953, the lake has been almost completely 
barren of these plants. 

At first this deterioration was attributed to spring 
floods, such as those that may have affected the Chau- 
tauqua flora. However, aquatic plant beds failed to re- 
cover when water levels were favorable to growth (with 
the exception of 1952 and 1953), and this reduces the 
possibility that floods were solely involved in tlioir de- 
cline. 

There is evidence that factors other than luriiiililv 
may be responsible for the eradication of aquatic plants 



in certain areas. Coontail, longleaf and sago pondweeds. 
and wild celery have disappeared from the Starred Rock 
Pool since the 1940's and have not returned, even though 
in many years since then the transparency of the water 
has been adecjuate for their growth. Their failure to re- 
appear suggests that factors other than a lack of water 
clarity were responsible; at other lakes increase in water 
transparency has been simultaneous with an increase in 
vascular aquatic plants. 

The level of Rice Lake was artificially raised 2 or 3 
feet in the mid- 1940's. When this rise occurred the 
aquatic and marsh plants began to disappear. By 1950. 
360 acres of river bulrush (Scirpus fluviatilis) had 
dwindled to less than 100. By 1956 only 20 acres were 
left. Both coontail and white waterlily (Castalia tuber- 
osa) increased at first with lessened competition from 
American lotus. However, as the marsh disappeared and 
wave action increased, this churned up the bottom, and 
coontail declined from 522 acres in 1950 to none in 
1960. White waterlily went from 90 acres to zero in 
the same period. 

Several years ago water levels were raised in Spring 
Lake, not now connected with the river, to enlarge the 
lake area for recreation. This increased depth was ac- 
companied by a loss of about 200 acres of coontail and 
an equal area of river bulrush marsh. 

Clearing of bottomland forests for agriculture elimi- 
nated such food-producing trees as pecans and oaks 
which furnished food for some ducks. 

FISH 

At Havana, on the middle stretch of the Illinois 
River, some of the elderly citizens still talk of the special 
trains that used to bring Springfield anglers to Havana 
for a day's fishing. They also recall the carloads of live 
fish that were once shipped out of Havana to the New 
York City market. 

Largemouth bass [Microptcrus salmoides) were 
abundant enough in the river-bottom lakes so that one 
could make wages by catching them with a cane pole 
for the local market. In 1897. 13,061 pounds of bass 
were handled commercially at the Ha\ana fish markets 
(Cohen, Bartlett, & Lcnke' 1899: 71 . Between 1899 and 
1908 the commercial yield of largemouth bass increased 
322 percent (Forbes & Richardson 1919:149-150). 

During the past half-century man has so seriously 
damaged the habitat that the once great fishery at 
Havana, and elsewhere along the river, is now but a 
fraction of its former size. Increase in turbidity and 
sedimentation, chronic pollution, decrease in aquatic 
vegetation, virtual disapijcarance of fingernail clams, 
and reduction of food h.ihilat through drainage have 
contributed to this change. 

Perhaps the most important change in the fish fauna 
was the introduction of the carp (Cyprinns carpio) in 
the 1880's. Carp fitted well into the new environment 
and soon became the most important commercial s|iecies. 



14 



adapting to many of the changes in the river. The 
fishery of the river reached its peak in 1908, when about 
24 million pounds of fish were taken commercially. 
Carp made up nearly two-thirds of this catch. 

The great increase in the commercial fishery starting 
at the turn of tlie century appeared to result from the 
increase in water because of the diversion from Lake 
Michigan, the increased nutrients made available to 
fish-food organisms, and the population explosion of 
the carp. 

Since 1908 the Illinois River fishery has been de- 
clining (Fig. 7) ; data in this depth are not available 
for sport fishes. 

The gains in water area available to fish, brought 
about by the diversion of Lake Michigan water, began 
to be offset after 1907 by the drainage of bottomland 
lakes. The 1913 area was about the same as it was in 
1897, prior to diveision (Forbes & Richardson 1919: 
154). In addition to these losses due to draining, condi- 
tions were further aggravated by the increase in sedi- 
mentation discussed earlier. Pollution from the Chicago 
and the Peoria-Pekin metropohtan areas has had serious 
efl'ects on the fish and fish-food organisms since the peak 
of the fishery in 1908. The upper river was more dras- 
tically affected than the part below Utica. Between 
1912 and 1917 pollution completely wiped out the fish 
life above this city (Thompson 1928:301). 

Forbes & Richardson (1913:517, 521-522) stated 
that near Morris (Marseilles Pool) in August and Sep- 
tember of 1912 the river "was practically destitute of 
fishes, and the few taken were in close pro.ximity to the 
Mazon slough. Moreover, some of the bullheads were 
'fungused' or in otherwise unwholesome condition. 



"The only other vertebrates taken here were a single 
frog, two sna]jping turtles, and a soft-slielled turtle. The 
search for moUusks yielded seven species of mussels, all 
the specimens dead, however, except for one collection 
made in Mazon slough. ... In August and September, 
1912, [Marseilles] conditions were similar to those found 
at Morris at the same time. Set-nets were raised every 
day from August 13 to 17, but witiiout result; and a 
dozen half-pound sticks of dynamite were exploded, hut 
no fish were taken. . . . On the night of August 19, a 
heavy rain, which flooded the small creeks, washed fishes 
out into tlie river, where they became sick from sewage 
and could be picked up easily with a dip-net." 

In the summer of 1923 the ri\er was practically 
anaerobic as far down as Cliillicothe, with conditions 
virtually impossible for the existence of fish (Greenfield 
1925:24-25). 

There has been a change toward the better in the 
upper river since then. Today fish are found living in 
the river above Utica. The goldfish (Carrasius auratiis) , 
an exotic fish not present in tlie river prior to 1908, now 
occurs commonly in the upper reaches, together with 
carp, black bullheads (Iclalurus mclas) , emerald shiners 
(Notropis atherinoides) , and other less abundant species. 
The return of fish life to this part of the river dining 
the late 1930's followed the better treatment of Ciiicago 
wastes and the slowing of the river's current following 
the building of the navigation dams. 

From a comparison of modern studies with those 
made befoie 1908, it appears that we may have lost 18 
species of fish from the Illinois River (Starrett & Smith, 
unpublished) . Many species now occur less abundantly 
than in former years. 



25.0 




COMMERCIAL FISH YIELDS FROM 
ILLINOIS RIVER 1894-1964 



1894 1897 1899 



1921 1922 



' 1931 ^ 1950 1955 I960 1964 



YEAR 



I 



Fig. 7.- — Changes in 
coninurcial fish yield in 
the Illinois River from 
1894 to 1964. (Data 
based on published fed- 
eral fisheries statistics 
and observations made 
by the Illinois Depart- 
ment of Conservation 
and Natural History 
Survey. Data for 1 955, 
1960, and 1964 from 
Starrett, Lopinot & 
11, nth. im])iiblished. ) 



15 



In the past 15 years the commercial fishery of the 
middle river, from Hennepin to Beardstown, has shown 
a sharp decline. The commercial yield in this stretch 
has dropped from 5.07 million poimds in 1950 (Starrett 
& Parr 1951:18) to 0.91 million pounds in 1964 (Star- 
rett, Lopinot, & Harth, unpublished), a reduction of 
4.16 million pounds. Because of the condition of the 
water in the river, the commercial fishery above Hen- 
nepin has been limited to the activities of one part-time 
fisherman who fishes near the mouth of the Fo.x River 
near Ottawa. 

No attempt will be made here to discuss the condi- 
tion of the populations of all fish species living in the 
river, but certain important species are included for 
closer scrutiny. 

Carp 

Since carp is the only species of fish that occurs 
abundantly in all sections of the river it has been used 
in our studies as an indicator of the effects of pollution. 
Much of the decline in the commercial catch since 1950 
has resulted from the scarcity of carp of commercial 
size (17 inches or more in total length) in the middle 



section of the river. Small carp are often abundant in 
this section but most of them disappear before attaining 
commercial size. The commercial catch of carp in the 
Alton Pool has changed little since 1950. 

1 here are two noticeable effects of pollution on this 
species. First, the length-depth ratio of individuals goes 
up with increasing pollution. By dividing the depth into 
the standard length, an index is obtained which, if 3 or 
greater, indicates that the fish is too thin for commercial 
uses. Any index under 3 would indicate a satisfactory- 
commercial fish. Second, carp exhibit a rachitic bone 
malformation (an abnormality characterized bv mal- 
formed heads and gill covers) known as a '"knothead" 
condition. This becomes more conspicuous (Fig. 8) 
with increased pollution. 

Thompson (1928) found that carp developed the 
knothead condition in association with the polluted 
condition of the river during and following \Vorld War 
I. Fig. 9 shows the percentages of the carp population 
having the knothead condition in various parts of the 
river, as reported by Thompson ( 1928:302) and in our 
checks in 1963. Upstream from Peoria, conditions were 
similar in 1926 and 1927 to those in 1963. The absence 



Fig. 8. — Knothead condition 
in carp. Left, normal: center, 
moderate knothead condition ; 
right, extreme knothead condi- 
tion. (From Thompson, 1928.) 






JOUET. 



Fig. 
heads i 
Illinois 
(Thoin 
(lllinoi 
data 



9. — Percentage of knot- 
n carp populations in the 

River in 1926 and 1927 

pson, I92fi) and in 1963. 

Natural History Survey 



BEARDSTOWN 




100 120 140 160 ISO 200 

MILES FROM MISSISSIPPI RIVER 



16 



Fig. 10. — Ratio betwctn 
standard length and body depth 
in carp in 1963 from Hardin to 
Morris. Note the change in 
length-depth ratio at Beards- 
town. ( Illinois Natural History 
Survey data.) 



CARP 

RATIO OF STANDARD LENGTH TO BODY DEPTH 



BEARDSTOWN 
MEREDOSIA . \ 



;2.60 
270 
^2.80 
="2 90 
^3 00 



20 



tSSSSMESS 




THll I iroTHF SPRING VALLEY 

chillicothe , ottawa | 

peoriaX henry \utica 

PEKINu^^^^ 



ILA GRANGE POOLl 



11963 



80 



100 120 140 160 180 200 

MILES FROM MISSISSIPPI RIVER 



of fish life above Utica in the 1920's prevented Thomp- 
son from extending his study as far upstream as we did 
at the later date. The percentage of knothead carp 
between Beardstown and the Peoria-Pekin area was 
greater in 1963 than it was in 1926 and 1927, indicating 
a greater pollution load in this stretch of the river. 
Stating this another way, it appears that the pollutional 
factors in the river responsible for this condition in carp 
have not increased above the Peoria-Pekin area, but that 
they have moved on downstream toward Beardstown 
since Thompson's observations were made. 

The length-depth ratios of carp caught in oiu' 
autumn 1963 Illinois River collections clearly indicate 
a sharp distinction between specimens taken above and 
below Beardstown (Fig. 10). Those below this city had 
ratios less than 3. and above it the ratios were 3 or more. 
\Vc suspect that this dift'erence may be due in part to 
ihc elimination of fingernail clams abo\e Beardstown. 
Slarrett & Paloiimpis (unpublished) have found these 
mollusca regularly in the stomachs of carp collected in 
the lower river. 

Carp in the niiddk- and upper river are subject to 
lower dissolved oxygen conditions than those in the 
lower river. It is possible that tlie life expectancy of the 
fish above Beardstown is reduced because of periods of 
stress resulting from oxygen deficiency. These two 
factors — l(;ss of fingernail clams ]5lus low dissolved 
oxygen — could explain the dearth of commercial-size 
carp in the middle and up|)er reaches of ihc Illinois 
River. 

Catfishes 

Black bullheads are still abundant in lh<' river, par- 
ticularly in the middle and upper stretches. These fish, 
together with carp, furnish most of the river fishing 
for pole-and-linc fishermen from Morris downstream. 
CMiaiincl catfish [Iclalurits jntnclalui) Iiave declined in 
abundance in the river since 1899 as evidenced by the 
following commercial fishing statistics: 241,000 pounds 
in 1899 (Forbes & Richardson 1920:183). 105..5.54 
jjounds in 19;')0 (Starrctt & Parr 1951:18), and about 



98,000 pounds in 1964 (Starrett, Lopinot. & Harth. 
unpublished). Mc.st of the catfish are now taken in the 
lower river. 

BufFalofishes 

The bufTalofishes of the genus Iclobius are now 
found mainly in the middle and lower sections of the 
river. Commercial catch statistics indicate that these 
important fishes have declined in the past 65 years, with 
the decline being the most rapid in the last 15. The 
1964 commercial catch was only about half that of 
1950. 

Crappies 

()ur data indicate very little change in crappie 
(Pomoxis annularis and P. nigromaculatus) populations 
in the lower river since 1 942. However, the decline in 
the middle river has been alarming. A Natural History 
Survey crew in 1942 (Thompson & Hansen, field notes) 
caught six times more crappies in nets than we were able 
to take by the same method in the middle river in 1964. 
\X Bath, by electrofishing. we caught 14 cra|)pies pei 
30 mimites of fishing in 1962, and only 4 in the same 
time in 1964. We suspect that the drastic decline has 
been due to the low oxygen conditions in association with 
the low water levels of the past few years. 

Bluegill 

The bluegill (Lcpomb macrochirui) has declined in 
out river collections even more than have the crappies. 
The take of bluegills in our 1942 fishing in all pools was 
33 times greater ih.ui in 1961. 

Largemouth Bass 

W'c have aliiaily meiuioiu'd the abundance of this 
fish at the turn of the centui-y. Other than in a few 
bottomlaml lakes, sport fishing foi- laigemouth bass is 
now rare in the Illinois River. In 1962 we made a few 
sizable collections from some parts of the middle and 
lower river. In 19615 and 1964 our electrofishing catch 
was substantially less in most parts of the river. The 
decline has been related to pollution and the loss of 
good habitat, as in the ease of other spot t fishes. 



17 



WATERFOWL 

Our emphasis, earlier in this report, on the great 
reduction in the quantity of vascular water plants has a 
special application here. These organisms form the base 
of the food pyramid upon which many other kinds of 
life depend. Crustaceans and aquatic insects occur abun- 
dantly on water plants. Such animals, as well as the 
plants themselves, form a part of the diet of various 
aquatic birds. The absence of these and other aquatic 
organisms can become limiting factors for some water- 
fowl populations. The disappearance of the fingernail 
clams and other bottom fauna created a drastic loss in 
the food supply of most diving ducks that inhabited the 
Illinois River valley. 

Anderson (1959:316) found that mollusca made up 
more than 85 percent of the diet of lesser scaup ducks 
[Aythya affinis) . The ring-necked ducks [Aythya col- 
laris) made mollusca about 25 percent of their diet, and 
the food of canvasbacks {Aythya vallisincria) was made 
up of about 9 percent mollusca. 

The combined loss of aquatic plants and bottom 
animals has drastically affected the numbers of diving 
ducks that use the Illinois during their migrations. Just 
as the loss of mollusca apparently caused problems with 
the lesser scaup, the loss of vegetation in Spring Lake, 
near Manito, has affected other species. Coontail pro- 
vided food for several thousand redheads [Aythya ameri- 
cana) during the spring migration. Now the redheads 
are forced to seek food elsewhere. Peoria Lake, once the 



scene of the greatest fall concentration of diving ducks 
in Illinois, has suffered an almost complete loss of these 
birds. 

Many dabbling duck species as well, such as the 
widgeon (Marcca amcricana) and the gadwall (Anas 
strepera), are well known to be dependent on water 
plants for food. 

Let us briefly examine some f)opulation statistics for 
a few important duck species. 

Lesser Scaup 

Fig. 1 1 shows the yearly change in lesssr scaup pop- 
ulations in both the Illinois and Mississippi river valleys 
from 1946 to 1964. Both rivers are included to indicate 
the possibility of change of duck populations from one 
valley to the other. Prior to 1955 the bulk of the fall 
population of this species was concentrated in the Illinois 
River valley. A tremendous decline occurred among the 
lesser scaups stopping along the Illinois in 1955, and 
numbers have remained insignificant since then. This 
reduction is synchronous with the disappearance of 
fingernail clams. It would appear that, after 1956. some 
elements of the Illinois River scaup population gradually 
shifted to the Mississippi. Although this shift could ac- 
count for a part of the previous Illinois River popula- 
tion, Fig. 1 1 indicates that the total population for the 
state has been substantially reduced. ^Ve might infer 
that the Mississippi Ri\ er docs not contain enough food 
to support a population of lesser scaup such as was 



LESSER SCAUP 



2,520,000-1 



ILLINOIS RIVER VALLEY 
MISSISSIPPI RIVER VALLEY 




1,200,000 



> 1, 000,000 



800,000 



600,000 

K 
lij 
SI 



400,000 



< 200,000- 



1946 '47 



1946 to 1954 



1955 to 1964 



Fig. 11. — Changes in Irsscr scaup duck populations on the Illinois and Mississippi ii\er valleys from 19-lti to 196.1. The reduced 
populations after 1954 coincide with the virtual disappearance of the fingernail clams from the river above Bcardstown. (Illinois 
Natural History Survey data.) 



18 



I 



present on the combined rivers from 1946 lo 1954, for 
iheir decline was greater than that for the flyway as a 
whole. 

Ring-necked Duck 

Ring-necked ducks were at a peak in numbers in 
1949 when aquatic plants reached maximum abundance 
in Peoria Lake (Fig. 12). With the decline in abun- 
dance of both aquatic plants and mollusca in the Illinois 
River valley, populations of these ducks declined. In the 
1955-1964 period the number of ring-necked ducks did 
not decline proportionately so much as did the lesser 
scaups. The ringneck seemed to be better able to use 
the flooded moist-soil plants for food. Moreover there 
was some decline in the populations of this species in 
the Mississippi area for several years after 1955. The 
decline probably reflects a known decrease in flyway 
population from out-of-state causes, for there was no 
commensurate deterioration in habitat conditions in the 
Mississippi valley. 

Canvasback 

Populations of this species slumped as badly as did 
those of the lesser scaup following the loss of plant and 
animal food resources from the Illinois River valley 
(Fig. 13). The canvasback population in the Mississippi 
River valley increased during the 1955-1964 period, fol- 
lowing the great disappearance of these birds from the 
Illinois system, but the total population for the state is 
still far below the pre-1955 level. Canvasbacks in the 
Mississippi River section of Illinois are forced to feed 
almost entirely on animal life because of the scarcity of 



aquatic vegetation, yet food-habit studies (Anderson 
1959; Cottam 1939) show their preference for aquatic 
plant foods. 

The paucity of plant-food resources in the Mississippi 
River section probably limits the numbers of canvas- 
backs to a level far below that accommodated by both 
river valleys in the early 1950's. 

Ruddy Duck 

The ruddy duck {Oxyura jamaicensis) declined in 
numbers with the decline in aquatic plants and mol- 
lusca (Fig. 14), but this decline was proportionately less 
than in other diving ducks, possibly because of this spe- 
cies' propensity to feed on aquatic insect larvae (Ander- 
son, loc. cit.). Insects have not as a group suffered 
catyclismic losses as have the mollusca in bottomland 
lakes. Therefore more animal food to the liking of ruddy 
ducks remains available in this valley. The Mississippi 
River seems to have absorbed a part of the Illinois River 
population, as in the case of other diving ducks, but it 
appears that the "carrying capacity" of the Mississippi 
may not be sufficient to overcome the loss of the food 
resources in the Illinois. 

Mallard 

Populations of this common duck (Anas plalyrhyn- 
chos) in the Illinois and Mississippi river vallevs do not 
show the same trends as do the dixing duck pojjulations, 
or those of the dabblers dependent on aquatic vegeta- 
tion. Although mallard populations declined after 1955, 
this decline occurred almost equally in both valleys; no 



RINGNECK 



900,000 



nn] = ILLINOIS RIVER VALLEY 
■ = MISSISSIPPI RIVER VALLEY 




150,000 



1946 47 



360,000-. 



^ 300,000 



,240,000 



z 

o 180,000 



120,000- 



60,000 




1946 10 1954 



1955 to 1964 



Fig. 12. — The ring-ncrkrd durk drrlinrd in abund;inrr in the Illinois Ri\rr following thr loss of the- molUisi- food rcsourci- and 
tlic reduction in aquatic vegetation. (Illinois .Natural History Survey data.) 



drastic reduction occurred solely in the Illinois River 
valley (Fig. 15). 

The lower mallard population in Illinois following 
1955 is attributed almost entirely to loss in production 
resulting from drought on the northern plains breeding 
grounds. The decline in mallard numbers in Illinois did 
not parallel the loss of aquatic plant and animal food 



resources. The mallard in Illinois feeds mainly on waste 
corn and the seeds of moist-soil plants (Anderson 1959) : 
its sustenance is more stable, being to a large extent in- 
dependent of animal life or aquatic plants. 

Mallards have sufTered a greater diminution because 
of drought on the northern plains than have most of the 
diving ducks; lesser scaup and ring-necked ducks in 



CANVASBACK 



360,000- 






d 


^ 300,000- 


/ 


s 


1 


a 

hj 

= 240,000- 

lU 

u 


/ 


f 


g 180,000- 

s 

D 
Z 




sJi 


_l 


/ 


m^Bu 


? 120,000- 


/ 


mr 


ilR 


60,000- 


J 







010= ILLINOIS RIVER VALLEY 
■ = MISSISSIPPI RIVER VALLEY 



168,000 



!^ I40P00- 

lE 

lU 

o. 

Q 112,000- 



84,000- 



56,000- 



< 28,000 



1946 '47 '48 '49 '50 '51 

Fig. 13. — Canvasback duck 
aquatic vegetation and mollusca. 



52 53 54 55 '56 



58 



60 



populations declined drastically in the 
(Illinois Natural History Survey data.) 



61 62 63 64 
Illinois River 



m 



alle 



1946 lo 1954 
following the near disa 



1955 to 1964 
ppearancc of 



RUDDY DUCK 



72,000 



u 60,000- 

o 

Ul 

i 48,000 



£ 36,000 

s 

Z 
-I 

? 24,000 



12,000- 



\ \ 



El = ILLINOIS RIVER VALLEY 
■ = MISSISSIPPI RIVER VALLEY 



1946 47 48 '49 '50 




36,000-1 



Si; 30,000 



a 24,000 



18,000- 



12,000- 



< 6,000- 



I 



l»46 10 1954 



1965 10 1964 



lig. II. — Ruddy ducks feed on both .small mollusca and aquatic in.srct larvae. Because aquatic insect lar\ac did not decline in 
abundance so much as the mollusca, these ducks persisted in greater numbers, proportionately, after 1954 than did other diving ducks. 
(Illinois Natural History Survey data.) 



20 



MALLARD 



7,200P00 



6,000,000 



4,800,000- 



3,600,000 



2,400,000- 



1,200,000- 



ILLINOIS RIVER VALLEY 
MISSISSIPPI RIVER VALLEY 




3.600.CX)0- 












o: 






• 


< 








UJ 








> 








^3,000,000- 












UJ 












Ol 












o 












lU 












5 2, 400,000- 












v> 












z 












llJ 












o 
























m 1,800,000- 
























2 












3 












Z 












o 1,200.000- 












q: 










^^^ 


bJ 




■.■.■.■.\-.-. 


























^^H 




^^H 


600,000- 






1 




1 



1946 10 1954 



1955 to 1964 



Fig. 15. — The mallard duck feeds primarily on plant foods, largely seeds of moist-soil plant.s and waste crop grains, so its pop- 
ulation was not affected by the loss in mollusca and aquatic vegetation. The population decline in Illinois reflects the continental 
trend for this species. (Illinois Natural History Survey data.) 



particular have escaped severe drought losses. In spite 
of their greater productivity during this drought period, 
the lesser scaups and ring-necked ducks, as well as other 
diving ducks in the Illinois River valley, declined in num- 
bers proportionately much more than the mallard. 

The difference in the geographic and yearly popula- 
tion change between the mallard and the diving ducks 
fortifies our belief that the post- 19.55 diving duck popula- 
tion loss is directly related to the loss in food resources 
resulting from silting, and from inban and industrial 
pollution of the Illinois Ri\er and bottomland lakes. 

To generalize, it would appear that recent environ- 
mental changes in the Illinois River, due to activities of 
an enlarging human population, have produced dis- 
astrous consecjuences on food resources for diving ducks 
as wtII as for some dabblers. From the mid-1950's to 
the present, a combination of soil pollution jjIus indus- 
trial and domestic pollution appears to ha\c eliminated 
as a functional ])art of the (•n\ir()nmcnt tin- important 
aquatic plant and animal life necessary for the support 
of populations of many species of ducks. 'I'hesc may not 
be the only factors involved; we do know that in certain 
[jlaces the raising of water levels, for examjjle, has con- 
tributed to the decline of a(|uatic vegetation. 

OTHER BIRDS 

A study of any group of species of birds will show 
fluctuations in numbers from year to year. Some of these 
changes in bird populations in the Illinois River valley, 

although rons])icuous. cannot be tiarcd to the deteriora- 



tion of water ciuality in the river. For example, the pro- 
thonotaiy warbler (Protonolaria citrca) was abundant 
near Chautauqua Lake 15 years ago and is now moder- 
ately rare. It is a cavity-nesting, insectivorous species, 
and at the time of its abundance there were many dead 
willows along the edges of the lake. The warblers used 
holes in the trees for nesting. As the trees decayed and 
fell, the numbers of the birds decreased, and the logical 
explanation for this population reduction is the disap- 
pearance of nesting sites. 

Changes in some other sjJecies may have a moie di- 
rect relationshi]) to changes in the river. 

Cormorants 

Each autumn during the 1940's and the early I950's 
there was a large flight of double-crested cormorants 
(Phalacrocorax auritus) down the Illinois River valley. 
The migrants usually arrived between October 5 and 9. 
Many thousands remained until early November, con- 
ducting fishing drives in the larger bottomland lakes. 
On October 16, 1950, we estimated that there were 
15,000 cormorants on the lakes in the valley between 
Spring Vallev and Meiedosia. 

The largest single flight of cormorants was ob.served 
on October 7, 1940, when an estimated 12,000 passed 
Havana. Another flight of approximately 9.500 |jassecl 
that city on October 9, 1949. 

A rapid decline in the numbers of cormorants visit- 
ing the Illinois River valley occurred after 1950. The 
largest passage in 1955 occurred on October 14, w^hen 
4,000 were estimated. By 1958 the great passage of cor- 
morants had dwindled to onlv SOO which were observed 



21 



Table 2. — Approximate number of nests of great blue herons and American egrets in heronries in the Illinois Ris'cr valley. 1958- 
1964, based on counts made from a circling light aircraft. 

V 1958 1962 1964 

Location of Great Blue American Great Blue American Great Blue American 

Nesting Colony Heron Egret Heron Egret Heron Egret 

LakeDepue 250 250 250 300 75 120 

Wise's Lake 60 

Pekin Lake 125 125 280 iM) 60 75 

Clear Lake 110 100 110 

Ingram Lake 250 

Meredosia Bay 90 500 1 50 

Total 775 375 J, 140 640 385 305 



on October 5. From 1959 to 1965 veiy small numbers 
of cormorants, usually fewer than 200, have been ob- 
served at any one time in the autumn. On October 18. 
1965, only 22 cormorants were observed on an aerial in- 
ventory of water birds in the Illinois River valley. This 
was the largest number seen in 1965. 

We do not know the cause of this decrease in num- 
bers of cormorants migrating through the Illinois River 
valley, but somewhere along the line a great change in 
their environment must have occurred. 

Herons and Egrets 

There is a subjective feeling that the great blue heron 
(Ardea herodias) exists on the Illinois River in diminish- 
ing numbers, and it appears fairly certain that although 
the numbers of American egrets [Casmcrodius albus) in- 
creased until 1962 there has been a decline since then. 
Our data, however, cover such a short span of time that 
they do not present a strong basis for evaluating long- 
term population trends (Table 2). Nesting populations 
of these two species have fluctuated considerably from 
19.58 to 1964. 

Counts of great blue heron and American egret nests 
were made at several heroniies along the Illinois Ri\er 
in June, 1939. A direct comparison of these nest conc<'n- 
trations with those of more recent times is not possible, 
for several of them have been vacated and new ones 
created. However, the nest data suggest that the num- 
bers of great blue herons ha\c declined and that the 
numbers of American egrets have increased. Only 17 
egret nests were found in four heronries in 1939, while 
305 were located in three of the lieronries in 1964. 

CONCLUSION 

An attempt has been made in the preceding pages to 
make comparisons which relate measurable changes in 
fish and wildlife populations of the Illinois River and 
its bottomland lakes to human activity during the past 
ihrec-tiuarters of a century. Even though a tremendous 



amount of biological data is available for the river, there 
are still many areas where we know very little concerning 
the organisms which li\ e in or have lived in this habitat. 

Some things become apparent from this study. Noth- 
ing in our physical environment ever remains static: 
change is the rule. But in this period in historv" when 
people are gaining more and more mastery over their 
environment, they have bent their intelligence toward 
making unusual changes that may benefit them temjx>- 
rarily but may be deleterious when a longer period is 
considered. 

It is unrealistic to delay doing things which benefit 
people until we know all of the possible side effects which 
may go along with these actions. If we were to do this 
there would never be any progress. But when such side 
effects become apparent and are not good, and there are 
ways of circumventing them, we do not use our intel- 
ligence if we fail to make corrections. 

It is difficult to believe that so much has happened 
to the Illinois River and its floodplain since Kofoid pub- 
lished his comprehensive work in 1903. Starting with 
the diversion of Lake Michigan waters into the river in 
1900. the ecology of this stream has been changed dras- 
tically several times. This diversion added to the fish 
liabitat in the lower stretches and remo\ed it completely 
in the upper river. Drainage enterprises removed half of 
the floodplain that the river once used and eliminated 
fish and waterfowl habitat. Navigation dams created 
new water areas while destrcning important waterfowl 
marshes. Domestic pollution has fluctuated up and down 
as new sewage treatment plants have been activated and 
then found to be inadecjuate as the rising tide of human 
population in the basin caught up with them. Chemicals 
ha\e been released into the waters from developing in- 
dustries on the river's banks and in the watershed. 

Although these actions have caused conditions to fluc- 
tuate widely, the net result has been an ever-diminishing 
biological resource as the aquatic habitat and its inhabi- 



22 



Fig. 16. — A carp-goldfish 
hybrid collected from the pol- 
luted upper Illinois Ri\er. Note 
the eroded tail and fin.s. 




tants have been degraded by the activities of man (Fig. 
16). Here and there man has tempered this degrada- 
tion — wildlife refuges and public hunting and fishing 
grounds have been established, and management of some 
areas by hunting clubs has produced better habitats than 
existed prior to this activity. 



We trust that the deleterious trends now apparent in 
the Illinois River can be changed. Some of the knowl- 
edge of how to do this is now available. More must be 
gained. There must be the desire on the part of agricul- 
ture, municipalities, industn', and individuals to trans- 
late present knowledge into action. 



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23 



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(89820-8000— 6-66 > 



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