Work object – Vyžuona river, which has 26 km lenght, is left affluent of Šventoji river, belongs to subbasin of Šventoji river and runs from northeast to southwest of Lithuania. Work aim – identify water quality and bounded with it live organisms of Vyžuona river. Work tasks – analyse physical-chemical water parameters of Vyžuona river, identify varietal composition of organisms, define and evaluate contamination of river objects. Work results – After the reasearch was made there was defined that Vyžuona river in Utena town (1 km from Krašuona river and Vieša river junction) belongs to average contaminated rivers category measuring by parameters of water quality: common nitrogen quantity 1.9 times exceeds permissible quotas, 68.6 % of common nitrogen is composed of nitrate nitrogen, BDS7 quantity 2,7 times exceeds the LDK, concentration of phosphates 2.3 times exceeded permissible quotas. Krašuona river and Vieša river runs trough private houses section, which has no central sewer and that is the reason why mentioned rivers are bearing domestic contaminants into Vyžuona river. According to 2004-2006 data below the outlet from drain mechanism of UAB „Utenos vandenys“ refinement system there was found concentration of phosphorus which averagely 1,75 times, common nitrogen 1,1 times and BDS7 1,7 times less in comparison with river part in centre of Utena town above UAB „Utenos vandenys“. That may be explained by UAB „Utenos vandeys“ affect, which drains large amount of enough... [to full text]