PART II: MATERIALS AND METHODS 

 Aquatic Communities and Water Quality 



We conducted a literature search to find published information on 

 aquatic communities and water quality in the study area before and 

 after the dams were constructed. Unpublished results of biological 

 surveys on the Illinois River were available in the files of the 

 River Research Laboratory at Havana. Some recent unpublished informa- 

 tion on water quality, benthos, and plankton in Meredosia Lake was 

 obtained from the Water Quality Section of the Illinois State Water 

 Survey at Peoria. A pre-publication version of a compendium on the 

 fisheries of the upper Mississippi River was supplied by Mr. Jerry 

 Rasmussen, coordinator, Upper Mississippi River Conservation Committee. 

 We also contacted fishery biologists in the Illinois and Missouri 

 Conservation Departments. Mr. Larry Dunham, special projects staff 

 biologist, Fisheries Division of the Illinois Department of Conservations 

 graciously supplied recent statistics on the commercial fishery and a 

 copy of a Ph.D. dissertation, "The Development and Current Status of the 

 Upper Mississippi River Commercial Fishery" (Sullivan, 1971). 



In order to identify the immediate and direct effects of construc- 

 tion of the navigation dams, we tried to find water quality and biological 

 surveys which had been done just prior to, and just after the dams were 

 constructed. In some cases, the only available pre- and post-impoundment 

 data were widely separated in time. We used these data, if the sampling 

 methods were comparable, and tried to distinguish changes attributable 

 to navigation from changes attributable to other factors, such as 

 pollution. If information was not available on the study area, we 

 tried to find information on comparable areas outside the study area. 



