The report deals with various microbiological methods to positively quantify Salmonella, fecal coliforms and standard coliforms; confirmation studies of bacteria growing on Bismuth Sulfite Agar; and diffusion cell studies of the survival characteristics of Salmonella bacteria in Fort Loudoun Reservoir. The difficulties encountered in confirming the presence of pathogenic Salmonella in mixed cultures prevented accurate quantification. This was due to similar cultural characteristics of other enteric organisms. Alternative procedure employing diffusion cells excluded the interfering organisms and permitted useful measurements of environmental effects on pure cultures of pathogenic Salmonella.