One of the major technical problems in maintaining present water quality is in the field determination of non-human fecal pollution, especially that resulting from bovine and other ruminant farm stock. The presence of a bio-indicator microorganism unique to the feces of these animals, but ubiquitous in terms of its presence there would aid in making pollution determinations. An organism selected was for this purpose was Caryophanon latum. Its selection was based on its presence in and restriction to ruminant fecal material. The report describes a study of the physiology of Caryophanon latum and the development of a selective medium for growing the organism to the exclusion of most, if not all, other organisms found in stream water. After development of this selective medium, the procedure was evaluated on sample stream waters with and without inoculation with the organism.