PART IV: IMPACTS ON THE FISH POPULATIONS OF THE ILLINOIS RIVER 

 Historical Impacts 



The Illinois-Michigan Canal (1848) 



The Illinois-Michigan Canal along the Upper Illinois River was com- 

 pleted in 1848, before any biological data were collected on the Illinois 

 River. It is unlikely that this canal had much of an impact on the mid- 

 dle and lower sections of the river, below Hennepin (river mile 208), 

 which are the sections most productive of fish and wildlife. The reason 

 they are the most productive is that the Illinois River below Hennepin 

 follows a large valley developed in the late Pleistocene epoch, and the 

 Illinois has developed lateral levee lakes, side channels, backwaters, 

 and marshes, which fill this ancient valley and provide excellent habitat 

 for fish and wildlife. 

 Chicago River reversal (1871) 



In 1871, the flow of the Chicago River was reversed in order to 

 conduct sanitary wastes from the city of Chicago away from Lake Michigan, 

 which served as the drinking water supply for the city. The polluted 

 waters of the Chicago River were directed through the Illinois-Michigan 

 Canal into the Des Plaines River, thence into the Illinois River. Some 

 of the polluted water apparently backed up into the lower reaches of the 

 Kankakee. The effect of the polluted water on the fishes of the Kankakee 

 and Illinois Rivers was dramatic according to a report of the U. S. Com- 

 missioner of Fish and Fisheries (Nelson, 1878):* 



"Previously to the opening of the Chicago River 

 into the canal in 1871, rockbass, ( Ambloplites rupestris ) ; 

 largemouth bass, ( Micropterus salmoides ) ; white bass, 

 ( Morone chrysops ) ; walleye, ( Stizostedion vitreum vitreum ) 

 mud-pike, (?) ; northern pike, ( Esox lucius ) ; mud eel, 

 (lamprey?); American eel, ( Anguilla rostrata ) ; buffalo, 



Modern scientific and common names of fishes have been substituted 

 for older names in the following quotation, wherever possible. 



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