The paper presents aquatic macroinvertebrate community at four investigated localities of the Gradac river. Sampling was carried out during 2003 and 2006. Community structure and composition, together with field data, were used to estimate the water quality status of the river. A total of 87 taxa have been recorded. Insects were found to be the most diverse component, especially Ephemeroptera. Insects were dominant in the regard of the quantitative structure of the community, as well. Recorded community indicates good water quality, ranged between oligosaprobic and beta-mesosaprobic status (1st-2nd class according national classification scheme).

The analysis of breaks and gaps frequences in the fish species Alburnus alburnus from different localities of rivers Kolubara, Sava and Danube, were showed the highest values that were above the presumed critical zone (3.0-3.5% of changes). At some of localities examined in May and October 2008, these values were much more elevated that the level of spontaneous changes normally seen in the controls in laboratory animals and in fish of relatively clean waters. Results that were obtained for these localities indicate to periodical or permanent contamination with genotoxic agents.

The paper presents the results of aquatic macroinvertebrates community analyses of the Milesevka river (Lim river watershed; Sava river basin) with aim to evaluate saprobiological status. Sampling was carried out on five localities during 2005. A diverse community (62 taxa) has been recorded during the investigation. Results of saprobiological investigation indicate satisfactory water quality, which is, according to national legislative, within 1st and 2nd quality class.

During the summer 2009 physical, chemical, biochemical and bacteriological analyses of water of rivers Mušnica and Suški Potok were performed. Microbiological analysis point out that waters belong to the 2nd class by Kohl. The river Mušnica had slightly polluted water, and river Suški Potok had very slightly polluted water. According to the Regulation on Classification of Surface Waters in Republic of Srpska (Bosnia and Herzegivina) all the observed parameters belong to the first or second water quality class. Only the stream Suški Potok has chloride concentration that exceeds a third-class quality. On the basis of observed characteritics it can be concluded that Mušnica and Suški Potok have a satisfactory water quality.