The relationship between the degree of pollution and the types of coliforms in the water of the Mochida, a rural stream in Matsue City, were investigated. Waters were sampled at 4 stations ranging from the nonsaprobic upper part to the saprobic lower part along the stream twice monthly from 12/Apr. 1972 to 13/Apr. 1973.
Coliforms were found in all samples, and the number of total bacteria, coliforms and E. coli increased parallel to the pollution degree. The ratio of coliforms to total bacteria number was about 3-5% for the all samples investigated. The ratio of E. coli to coliforms, however, was1-15%, and increased markedly with the pollution degree. Intermediate types dominated over A. aerogenes at the nonsaprobic upper stream. Most of E. coli and A. aerogenes isolated were identified to type I. Only one strain of pathogenic E. coli was found in 259 strains examined.