In recent works enzymatic phosphatase activity state as a new potential good indicator for water saprobity and trophic state in water. On water reservoir 'Grliste' reinstated monitoring on the base physico-chemical, microbiological and biological analysis from beginning works water factory 1990 but, from 1998 use of this new biochemical method in monitoring as reliable additional indicator in fast preliminary water quality and the ecophysiological state of water. According to the results obtained for index of phosphatase activity (IFA) (Matavulj, 1986) water of 'Grliste' water accumulation belongs to category 3-A (polluted water).

The examined period is characterized by small floristic variety and well advanced eutrophication process. By the phytoplankton qualitative analysis it has been noted the domination of Bacillariophyta algal division. The values of density on phytoplankton population and their biomass show the domination of bluegreen algae, before each other, that of the species Gomphosphaeria lacustris Chod. As the consequence of the eutrophication, these algae develop intensively, up to the degree of water blossoming. The very high concentrations of the primary and secondary nutrients have also been noted. The trophic status of the reservoir on the basis of OECD classification can be defined as eutrophic.

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.