In June-November 1995 on a small river Barnaulka investigations were carried out. 63 species of infusoria referred to 26 families from 11 orders of 3 classes were revealed. Endemics weren't found, 40 of them refer to ubiqvist, 33 are indicators of organic pollution level. At the river's mouth the river refers to beta-mesoorganic population level zone of contamination (vtfn index of organic pollution level makes up 2,29, it ranges within 1,5-3,06) in the place one km up the river refers to alfa-mesooganic pollution level one (2,6; 1.94-3,15 respectively).