The bacteriological quality of the Des Moines River from Des Moines, Iowa, to Lake Red Rock and the lake itself were studied on eleven sampling dates from July 1969 to May 1970. The examined river sites consistently had higher EMB plate counts than sites in the lake proper and counts from both river and lake were generally far above quoted standards of water to be used for contact and non-contact water sports. The pH readings were all within quoted normal ranges. The expected effects of seasonal variation and runoff on bacteriological counts were found. Seven isolations of pathogenic, enteric bacteria were made during this study. These isolates were made at the two sampling points closest to the Des Moines sewage treatment plant. XLD medium proved to be more successful than DCC or BG in isolating these pathogens. These results were examined in view of the expected heavy use of Lake Red Rock for recreational purposes
