Advancement in microbiology reveals new potentially pathogenic water borne microorganisms. Because of inconvenient water works, World Health Organization and legislators necessarily standardize guidelines and codes for potable water examination. Water works with safe water treatments and distribution systems obey the rules of routine control, and that is why they do not recognize more sophisticated sides of microbiological water quality. From that point of view, poorly studied slow growing chemoorganotrophic bacteria resistent to environmental conditions are interesting.

The role of forest belts for surface water protection has great importance in two geomorphological ambiances: plains and hilly-mountainous. Plains ambiances are concerned to regions where dominates wind erosion: Backa, Banat, Macva, sandy terrains (Deliblatska, Suboticko-Horgoska, Ramsko-Golubacka, Kladovska), spacious surfaces in surroundings of hydrosystem DTD, natural and artificial reservoirs, river beds. Hilly-mountainous ambiance is related to regions where dominates pluvial erosion: catchment areas of reservoirs for water supply south from Sava and Danube, Fruska Gora mountain and Vrsac mountains.

This paper presents the results of water quality analysis of the rivers Tamis, Plovni and Stari Begej, using the WQI method, for the time periods 1987-1991 and 1998-2002. It also show the trend of water quality of these water streams for two characteristic time periods, through trend of WQI index.

Faculty of Science, University of Kragujevac (Serbia, Serbia and Montenegro), has developed SeLar Information System (Serbian Lake and Reservoirs Information System) which provides all the information of Serbian lakes and water reservoirs. Information system is needed for transfer of knowledge and informations, cooperation among participant in management and support of sustainable using of water resources. The paper presents the basic system components and some applications examples.

Consequently to eutrophication, from the beginning of July to the end of November there was a water bloom in reservoir Celije generated by three cyanobacterial species. Monitoring of that phenomenon indicates that cyanobacteria have become phytoplanktonic dominant residents in the course of significant part of the year.

In this paper we have presented the results of the investigations of phytoplankton carried out in the river Old Begey, from April 2003 till February 2004. The presence of 116 algal taxa of which 10 Cyanobacteria, 20 Euglenophyta, 50 Bacillariophyceae, 3 Chrysophyceae, 30 Chlorophyta and 3 Dinophyta was recorded. In the river Old Begey some rarer brackish species Entomoneis alata and Bacillaria paradoxa have also been found. The index of saprobity given on the basis of Pantle-Buck method indicated that the quality of water of the river Old begey belonged to beta-alfa-mesosaprobic category.

One of major direction of algology development in Serbia is completing data about bioindicating values for saprobic system based on the existing list of bioindicators. This work shows the results of several year's investigation of macroalgae in streams that belong to the Danube river watershed. Altogether, 72 taxa belonging to six divisions were found in the investigated streams. They were as follows: Cyanophyta (34 taxa), Rhodophyta (8), Xanthophyta (6), Chrysophyta (1), Chlorophyta (22) and Charophyta (1). Analysis of the list of species found in streams of highland regions of Serbia and the List of Indicatory Species reveals that 50% (36) of the species found have definite indicatory values. This work presents the data obtained for species that are not on the existing lists of indicators.

Studies of the plankton copepods also included the area of continental shelf and the Southern Adriatic deep valley with pronounced ocean characteristics. The deep waters of Southern Adriatic are inhabited by numerous species of all depth zones, with a pronounced domination of ocean forms, similar to the Mediterranean. The quantity of copepods in the area of open surface waters shows a pronounced spring maximum of abundance. The abundance of overall copepod population decreases from the shore toward the open sea of Southern Adriatic valley, with an increase of species abundance in plankton. That area is governed by stenothermal and stenohaline conditions. The Copepoda community is characterized by stenothermic and stenohaline species. Ranges of many of these are not increased horizontally toward the northern parts of Adriatic, and the individuals carried north by water currents quickly die.