The paper deals with determination of the economic elements of water management, which reflect the specific foundations, processes, principles and goals that are determined by the water policy. In terms of services, this represents the economic valorization of the foundations in manageable and unmanageable technical and natural systems, in which processes take place to bring water to a certain target quantity and quality, as well as provide safety against water in time and space. The use of, and protection against water, are under the pressures and influence of natural climatic and soil factors, the balance condition of surface and groundwater, and in particular human activities and demands for the characteristics of water in a water body, water area and in the river basin. These factors influence the demand for services, which also depends on the available domestic product, its volume of use, tastes and preferences. The offer consists of services for a particular quantity and quality of the available water, and for a certain degree of safety from the harmful effects of water, which are achieved by the employees of the functional facilities and systems. Together with the activities of the association, population and public services, the use of, and protection against water make up the totality of water management. It requires a decision process in all of the functions involved in planning, organization, management and control. Water management is identified with the water policy and activity, although there is a difference between them. The first is represented by a decision-making system in planning, organization, management and control, while the second is represented by the activity systems of government in the field of protection against water, as well as the protection and use of water. The activity consist of certain services which are performed by the employees of the companies, through the provision and performance of water management services in various time and space, in accordance with the offer and the demands of the users.

This paper presents aquatic macroinvertebrate community composition at six investigated localities of Drina River. Sampling was performed during 2004. Field data together with characteristics of the community were used to estimate the status of the river. According to our results good water quality, within the limits of the 2nd category, was evaluated for Drina River.

In the spring/summer and autumn season of 2010 dynamics of macrozoobenthos structure of Moravica River was investigated after the changes in habitat caused by floods. It was found that macroinvertebrates are represented with 13 groups and 64 taxa from 54 genera. Trichoptera fauna was represented by 11 species, Diptera 10, 8 Ephemeroptera, Odonata 5, 6 Oligocheata, Gastropoda 5, Crustacea 3, 2 Hirudinea, Bivalvia 2 and Turbellaria 1. In average 11 taxa was identified in samples. Most abundant were Gammarus pulex fossarum, Grammarus balcanicus, Asellus aquaticus and Chironomus thumma. Abundance of macroinvertebrates at the downstream direction was increasing and was correlated with decreasing number of taxa especially in the spring season. Species are equal in number to the initial sites, and downstream a smaller number of species dominated. Average value of N-index was 2.1 which points to relatively favorable structure of macroinvertebrates. Average value of C of 0.32 indicates increased dominance of individual species. Saprobity index ranged from 1.6 to 3.5 at average of 2.3.

This paper presents the results of the Danube River water quality analysis based on the calculated SWQI index values, using the data set provided by the Hydrometeorological service of the Republic of Serbia for the year 2009. The relevant parameters are sampled once a month on average, at 16, measuring stations of the River Danube along the flow through Serbia. Data grouped on the sampling site basis, averaged on a yearly level, resulting in a median SWQI for each sampling station, are employed to obtain a synthesized quality indicator. Research shows that the overall quality of the water of the Danube in Serbia, SWQI = 85 for the given one-year period and to match the descriptive indicator very good water quality.

Land reclamation activity, such as irrigation, requires monitoring in order to create conditions for a stable and highly productive crop production. It is necessary to monitor the use of water for irrigation in order to prevent or mitigate the consequences of unfavorable, poor quality water on soil irrigation, cultivated crops or equipment. In the province of Vojvodina, the Detailed Channel Network has a great potential. The specificities of this source of water for irrigation need to be observed in the usability of water. In 2010 the sampling was conducted in selected localities in middle Backa and Banat. The results indicate that water quality does not always meet the requirements proposed by the applied classification. What is particularly unfavorable is the fact that the worst quality was registered during the survey conducted at the beginning of the irrigation season on all sites.

The paper presents results of microbiological quality of three drinking water sources – Ratno ostrvo, Petrovaradinska ada and Strand. The following analyses were carried out in 2010: total count of aerobic mesophilic bacteria at 37 deg C, count of organotrophs (categorization according to Kohl), aerobic facultative organotrophs, lipolytic and hydrocarbon oxidizing bacteria. Organotrophic count was determined on low nutritive R2A medium. Enzymatic activity of water was also determined and water was categorized according to index of phosphatase activity (IFA).

A contemporary biostability assessment of raw and treated water requires determination of biodegradable organic matter fraction responsible for bacterial growth. BDOC test allows monitoring of bacterial growth by assaying chemical changes in the test-water and thereby determine the content of biodegradable dissolved organic carbon (BDOC). The aim of this study was to optimize the required period for performance of BDOC tests, and to examine the use effectiveness of different biofilm carrier. The results indicate that the BDOC test with sand-inoculation is more effective compared to the anthracite, and recommendations for monitoring of biodegradation process are a period of 3-5 days.

The paper presents the results of preliminary study of the intestinal content in bream (Abramis brama L. 1758) of the Danube River through the Belgrade Region. The fishes were collected in May and October during the period 2007-2009 at two sampling sites along the course. A total of 42 fish specimens of different age (2+ to 6+) were examined. By examination of compositing of intestine of bream have been found members from macrozoobentho-groups – Oligochaeta, Gastropoda (Lithoglyphus naticoides), Bivalvia, Amphipoda (Gamaridae). Our investigation showed that the diet of bream is dependent of bottom fauna composition and structure.

Physico-chemical and microbiological analysis of Brvenica River water was conducted in period 2006-2010 and showed seasonal variations of water quality. The results of correspondence analysis indicated that the year 2006 regarding the physical and chemical characteristics of water, was different from the rest of the examined period. This year was characterized by the absence of ammonia, low contents of nitrite, iron and chlorine, and increased concentrations of KMnO4 consumption. In 2007 and 2008 presence of manganese in water, low concentration of KMnO4 consumption was detected as well increased turbidity and electrical conductivity. And the third distinguish period are years 2009 and 2010 when water was characterized by low concentration of NO3, and the presence of ammonia, NO2, and iron in the water, while turbidity was low and conductivity was average. In Brvenica River water Escherichia coli, Citrobacter sp., Enterococcus sp., Klebsiella sp. are detected. In year 2006 number of aerobic bacteria and total coliforms were rather low, while their number in 2008 is relatively high. Over the whole period, only in 2008 fecal streptococci were not detected. Other years are characterized by growth of aerobic bacteria and total coliforms and the occasional presence of fecal streptococci. Throughout the whole examination period fecal coliform bacteria were present in the water.

Research macroinvertebrates in the lower reaches of the River Veternica was conducted during 2008 in spring and summer season on nine sites, in period of reduced outflow of water from the Lake Barje, when the water level is often reduced to the biological minimum. The presence of 91 taxa from 13 groups of macrozoobenthos was detected. Groups of Diptera, Ephemeroptera and Trichoptera were presented with 18, while Megaloptera, Plesoptera and Nematomorpha with one taxon each. The spring has been allocated 69 and 70 taxa in summer. The average was separated 17 taxa. Average number of macrozoobenthos was 1440 ind/square m per site. The few types of macroinvertebrates were very abundant at the site before the river confluence into the South Morava River. Insects made up 66.4% of the total number of individuals, especially the numerous groups of Diptera with 45.7%, while the share of the group Aquatic amounted 31%. The largest shares of the total abundance of taxa were as follows: Chironomus thumma with 28.16%, Limnedrilus hoffmeisteri with 11.2% and Tubifex tubifex with 6.89% and Caenis macrura from 5.2%. The structural parameters indicate that diversity of macrozoobenthos reduces in downstream direction, reflecting degradation of ecosystems.