35 
3. ILLINOIS VALLEY LAKES, LiverRPooL To 3.5 MILES ABOVE BROWNING 
Mite 199.0—Mire 226 setow Lake MicHIcAN 
Lakes north of Havana, All mud bottom, 
Mile 199.0—207.0 Depths, 2—6 ft. 
Liverpool Lake 
Dogfish Lake 
Thompson Lake 
Quiver Lake 4* 
15 
wo o 
Lakes south of Havana, 
Mile 224.0—226.0 
Stewart Lake 5 
*In Quiver Lake five additional collections were made in the deep channel cut 
by the wash from Quiver ‘Creek and-in the sandy-muddy zone near the east beach. 
The Illinois River and Peoria Lake, Chillicothe to Wesley 
(Mile 146.5—167.8 below Lake Michigan) 
At all of the thirty-five lake and river stations between Chillicothe 
and Wesley where bottom dredgings were made in 1920, there was 
evidence in some form or other of deteriorating change since 1915. The 
various tests and observations made both in 1920 and five to seven years 
earlier had regard chiefly to the physical condition, appearance, and odors 
of the muds; the composition and abundance of the small bottom- and 
shore-fauna ; and the kinds, amount, and distribution of the coarse aquatic 
vegetation. While sharply drawn comparisons are not easy in the first 
group of items, bubbling and more or less foul odors having been noted at 
some stations between Peoria and Chillicothe in 1915, in the second item- 
ization we have to do with the disappearance since that year of whole 
families and numerous genera and species of small bottom-animals, as 
well as with the entrance in their place, in several instances, of new pollu- 
tional forms; and in the last, with the practically complete disappearance 
of a rich aquatic vegetation which formerly covered several square miles 
of shallow-lake territory at low water, along with the similarly complete 
extinguishment of a previously very rich shore- and weed-fauna. 
The muds taken at the eight stations in the “upper lake,” between 
Chillicothe and Spring Bay, were all strong in odor, and bubbling was 
abundant, when the mud was stirred, in all depth-zones. Both in the 
channel at Rome and Spring Bay and in the open lake opposite Rome 
a peculiarly spongy and foul-smelling mud was lifted by the dredge. 
These samples showed a_ texture not unlike freshly risen bread, and gave 
out a distinct blubbering sound on being pressed with the hand as they lay 
