365 



Lower Peoria Lake and Illinois River, Peoria Narrows 



to Peoria and Pekin Union Railway Bridge 



(Mile 161.0—166.4 below Lake Michigan) 



HVDK0GKA^HY 



In or adjacent to lower Peoria Lake in the summer of ]y"22 bottom 

 dredgings were made at eighteen stations in four cross-sections. Col- 

 lections began at the foot of Peoria Narrows, which is just above the 

 head of the lower lake wide-waters and is not far from a quarter of 

 a mile wide at recent low water, and ended at the P. P. U. Railway 

 Bridge across the Illinois River about a mile and a half below the 

 foot, which lies slightly below the center of the city of Peoria. The 

 two intermediate cross-sections through the lake proper were opposite 

 Workhouse Point, a little less than two miles below the Narrows ; and 

 opposite the foot of Fulton Street, a mile and a half below the first 

 open lake cross-section and less than a mile above the lake's foot. The 

 full width of the lake was somewhat more than a mile at the Point 

 and considerably less than a mile opposite Fulton Street, though a]i- 

 preciably wider in between, during the summer months of 1!)22. 



Though a good deal smaller, as measured either by length or 

 width, than the upper or the middle lake, being only about three aiifl 

 a half miles long as compared with nearly six for the middle lake and 

 more than six for the upper, the lower lake with its immediately con- 

 tiguous areas, as here regarded, presents a visibly greater variety of 

 habitats than either of the others, and differs from them also in several 

 other main features. Its entire lower half is narrowed to an efYectual 

 width of much less than a mile by a long submerged but formerly 

 wooded island on the east side, whose outside edge is only about three 

 quarters of a mile from tlie Peoria water-front opposite. The effect 

 of this is that throughout the central and lower portion of the lower 

 lake, where our main cross-sections were made both in ]!)22 and 1!I20. 

 the great body of moving water passes through a relatively narrow 

 and deep prism, with depths between twelve and fourteen feet pre- 

 vailing over a total width of nearly half a mile, and with, as a conse- 

 quence, a greater average current everywhere in the open portion than 

 in corresponding sections of the upper or middle lake. 



The west littoral of the lower lake receives the discharge from 

 most of the main sewers and industrial drains of a city of nearly 

 100,000 people, but although this is true, during the summer season 



