PART I: INTRODUCTION 



The purpose of this report is to compare the fish and wildlife 

 habitat in Pools 24 and 25 of the Mississippi River and Pool 25 of the Mississippi 

 and lower Illinois Rivers from before to after construction of 

 the navigation dams. The dates of construction and first operation are 

 given below (U.S. Army Engineer District, St. Louis, 1975: 4-13): 



The study reach of the Mississippi River extends from Alton, 

 Illinois upstream for 98.3 miles to near Saverton, Missouri (Figures 1 

 and 2). Charts of the upper Mississippi River have been prepared by 

 the U.S. Army Engineer Division, North Central, Chicago, Illinois (1975) 

 and locations are given in river miles, starting from mile 0.0 at the 

 intersection of the Ohio and Mississippi Rivers near Cairo, Illinois and 

 proceeding upstream to a point just above Minneapolis-St . Paul, Minnesota. 

 The study area of the Mississippi River used in this report extends from 

 Mississippi River mile 202.9 to 301.2. The navigational locks and dams 

 along the river impound waters, called pools, which provide convenient 

 reference to the geographic location of various sections of the study area 

 (see Figures 1 and 2) . 



The lower part of the Illinois is influenced by Dam 26 on the Mis- 

 sissippi. Charts of the Illinois Waterway have been prepared by the 

 U.S. Army Engineer District, Chicago (1974) and locations are likewise 

 given in river miles, starting from mile 0.0 at the confluence of the 

 Illinois and Mississippi Rivers, at Grafton, Illinois, and proceeding up- 

 stream to Chicago. The study reach cf the Illinois River extends from 

 mile 0.0 upstream to the LaGrange Lock and Dam at mile 80.3. Along both 



