Over the years, a variety of temperature and storage conditions have been recommended as a means of maintaining sample integrity when immediate coliform analysis was not possible. These recommendations were developed, in large part, from analysis of drinking water samples which usually have a low coliform and nutrient content. However, in river water samples with high (i.e. 100,000/100 ml) initial coliform densities showed that the population tended to increase, at both refrigeration (2-6C) and room temperatures (23-27C), when analyzed after 6, 12, and 30 hours of storage. It was found that the coliform population increases in the room temperature samples to be more than double those observed for the refrigerated samples.