69 70 



73 1974 



Figure 3. Mean water levels, mean discharge, and mean dissolved oxygen 

 levels during July and August and the number of largemouth bass 

 taken per 30 minutes of electrof ishing in the fall at Chillicothe 

 Island Chute (mile 180) on the Illinois River. 



Chillicothe Island Chute is in the Peoria Pool. Discharge was 

 measured at Marseilles (mile 247), water levels at Peoria 

 (mile 163), and oxygen levels in the chute. The oxygen reading 

 marked with an asterisk was taken on September 30. Water levels 

 were obtained from the "Missouri-Mississippi River Summary and 

 Forecasts," issued daily by the National Weather Service, River 

 Forecast Center, Kansas City, Missouri. Discharge was obtained 

 from an annual publication, "Water Resources Data for Illinois," 

 by the U. S. Geological Survey District, Champaign, Illinois. The 

 other data were obtained by the Natural History Survey. 



39 



