This paper is an abstract of the operative program for water protection in the Republic of Serbia (Yugoslavia) for the next five-year period of time. There is a short review on the present water protection status, particularly status of wastewater treatment plants. It includes layouts of water protection solutions in different fields, by priorities, as well as assessment of necessary capital investments for their implementation.

In order to carry out the program of protection and rational exploitation of Kovilj Marsh (Serbia, Yugoslavia), which is a part of special natural reserve called the Marsh of Kovilj and Petrovaradin, we have done an ecological analysis of the fish community. The research was conducted during the period of "low water", in the autumn 2000, on the following locations: Slajz, Tonja and Arkanj, and we have established the presence of 12 species from 6 different families. The saprobic index of the majority of bioindicative species shows that the water belongs to the beta-mesosaprobic type (the saprobic index according to Pantle-Buck is 2.1). The presence and abundance of certain ecological groups of fish is examined in relation to migration, type of food and type of substrate on which the fish lay their eggs. The results of this examination point to main features of certain localities in this floodplain, as well as to the necessity of taking appropriate measures of protection of this valuable water resource.

Determination of total organic carbon content (TOC) and trihalomethane formation potential (THMFP) as well as correlation of those two parameters is recommended for monitoring of water bodies which are considered as drinking water resources. Those parameters would enable a categorization of water bodies from the protection point of view as well as from view of their usage as drinking water sources. Relationship between TOC and THMFP is dependent on the origin and the structure of organic matter in water. In this paper the correlation of TOC and THMFP is given for different kind of resources.

Expert system (ES) is a software which unites mathematical models, empirical knowledge, expert evaluation, engineering intuition, heuristic rules and necessary informations which through the inference engine gives useful advise to the decision maker, to reach a correct and timely decision. The objectives of ES cover a wide range of tasks of protection of waters, out of which the following seem to be the most important: diagnostics, monitoring, estimation, interpretation, planning and design of systems, maintenance, trouble shooting, education, management.

Institute for Development of Water Resources Jaroslav Černi and the Republc Hydrometeorological Service of Serbia carried out detailed processing and analysis of available hydrometeorological data within the amendments of the draft for Water Management Master Plan of Serbia in 2009. In this particular case, the most important characteristics of time series of hydrological and meteorological parameters on key sections of hydrological and meteorological stations, their conventional processing and analysis was completed and updated. The final goal of amendments of the draft of Water Management Master Plan is to provide elements to define the balance of available water resources in the territory of the Republic of Serbia, necessary for defining the strategy of water use and defining the conditions for integrated and rational management. This paper presents the most important elements of water balance using modern GIS technology.

This paper presents hydrological parameters relevant for defining of water balance and water protection in the territory of the republic of Serbia. the parameters are taken from the Master Plan of the Republic of Serbia (2009) in which data processing was performed for 143 hydrological stations, 437 precipitation and 56 climate stations of the Republic Hydrometeorological Service of Serbia for the period 1946-2006. Data for pluviograph stations are taken from scientific and research base for the implementation of the VIS, where data processing was carried out for 30 pluviograph stations for the period from the beginning of the operation until 2008. For the purposes of making the Strategy for Water Use in Serbia, spatial interpolation of all relevant parameters respecting the altitude was carried out. The relevant parameters are presented in the form of GIS maps of isolines.

Scarce natural resources which are important for development of society or civilization itself are the issue of research for economists from the point of view of their efficient utilization. Theory of natural monopoly asserts that for society is better to treat scarce resources as monopoly than to put them on free market. The assertion is that it is better to invest in development of other markets than into free competition in sphere of some scarce resources. Main aim of this paper is to overview some elements of theory of natural monopoly.

Thermal waters represent an unused natural potential of Serbia. A possible way of utilizing this resource is to carry out the initiative that has been underway over the past several years to use certain thermal waters for the rearing of some allochthnous thermophilic fish species, the most famous among them being the group Tilapia (fam. Cichlidae), authochthonous in Africa and Asia. The analysis of basic physico-chemical properties of the Ovcar Banja (Ovcar Spa) thermal waters (the bed of the Zapadna Morava river, Western Serbia) indicates the possibility of their utilization for this purpose.