flocculent bottom muds that have been carried into the bottomland lakes 

 by the river (Starrett and Fritz, 1965). 

 Sanitary and Ship Canal (1900) 



On January 1, 1900, the Sanitary and Ship Canal was opened at 

 Chicago, connecting the Des Plaines and Illinois Rivers with Lake 

 Michigan. The canal was used to flush municipal and industrial wastes 

 into the Illinois River system and away from Chicago's municipal water 

 intakes in Lake Michigan. 



The quantity and quality of water diverted through the canal had a 

 tremendous impact on the Illinois River. Water levels at Havana, 

 Illinois rose an average of 2.8 ft and, during the normal low-flow period 

 between June and September, rose 3.6 ft (Forbes and Richardson, 1919). 



As a result the tree line along the river retreated and the loss 

 of mature pin oak and pecan trees meant a loss of food for mallard and 

 wood ducks (Mills, et al. , 1966). Populations of cavity-nesting tree 

 swallows and prothonotary warblers increased as a result of the increase 

 in nesting sites in zones of dead trees bordering the river and lakes. 

 When the last of the dead trees collapsed during the 1940' s, populations 

 of these species declined markedly. (Personal Communication, September 

 1974, Dr. Frank C. Bellrose, Waterfowl Biologist, Illinois Natural 

 History Survey, Havana, Illinois). 



One beneficial effect of the diversion was to increase the surface 

 area of water in lakes and backwaters, which apparently improved the 

 fishery (Forbes and Richardson, 1919). It is also likely that stumps 

 and snags, left after the trees had died, temporarily provided cover 

 for certain species such as largemouth bass, sunfish, and crappie. The 

 increased shallow water areas and nutrient loading of the Illinois River 

 and its bottomland lakes initially may have increased the plankton popu- 

 lations and the biomass of bottom fauna in the middle and lower river 

 (Forbes and Richardson, 1913). In the river proper, populations of 

 molluscs, especially fingernail clams, probably increased the most, with 

 a beneficial effect on mollusc-consuming species of adult fish, such as 

 carp, catfish, buffalo, and drum. 



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