AWWA ACE59829

Traditional uses of fecal bacteria as a method to identify the major contributors to nonpoint source pollution has recently been replaced by novel alternative methods such as microbial source tracking (MST). A critical question not adequately addressed in MST literature is the stability and distinctness of fecal bacterial populations once they have entered surface water. Therefore, this laboratory-based study was designed to determine if cattle, swine, and poultry manure had distinct populations of fecal coliform (FC) and fecal streptococci (FS) bacteria that could be identified statistically over time. Laboratory-scale mesocosms were created in triplicate for three manure sources: cattle, poultry, and swine. The average rate of decay for fecal bacteria in surface water ranged from -0.085 hr^-1 for FC in cattle manure to -0.140 hr^-1 for FS in swine manure. Discriminant analysis of the FC and FS species composition data indicated that distinct populations of fecal bacteria exist for each manure source examined. The rates of correct classification (RCCs) were highest in the FS species compositions with all three sources having RCCs of 100%. The RCC for FC species composition were lower than those for FS, with RCCs of 83.3%, 71.4%, and 100% for cattle, poultry, and swine, respectively. Distinct populations of both FC and FS appear to exist and can be classified correctly in surface water even in the presence of native bacterial populations. Based on the findings of this study, research into the development of an MST methodology based on fecal bacterial species composition is warranted. Includes 10 references, tables, figures.