One of the most important strategic-development directions of Serbia in the 21st century is restoration of hilly-mountainous regions. Stara Planina represents the region with extraordinary natural potentials almost unused, especially the part upstream of the reservoir Zavoj. Development of sheep raising on huge meadow-pasture surfaces in the catchment of river Visocica is possible, taking into account natural characteristics of the area, education and tradition of inhabitants. Catchment area of river Visocica provides water for water-supply reservoir Zavoj, so it is very important to apply erosion control measures on the slopes, as well as stopping the eroded material and pollutants before reaching the water courses. Agroforestry is optimal system of land use, with indispensable conservation and protective measures.

In this paper, results of seasonal investigations throughout 2002, important for evaluation of the eutrophication and bacterial pollution of the Montenegrin coastal sea were presented. It was established that the difference between warmer and colder periods of the year was highest in the part of the Montenegrin coastal sea exposed to the strongest impact of the open waters of the Southern Adriatic.

The process of removal of natural organic matter from groundwater by adsorption on powdered activated carbon, coagulation and flocculation was investigated. It was found that the combination of these processes yielded a decrease of KMnO4 values, which allowed the reduction of the coagulant concentration, needed to achieve the necessary quality of drinking water, up to 50%. Also, it was established that the sequence of adding powdered activated carbon and coagulant is one of the essential factors determining the efficiency of NOM removal from water, and which is primarily conditioned by the nature of the organic matter present in the investigated water.

Membrane processes is gaining broad application in potable water treatment. Experience in application of membrane system for treatment of potable water so far showed that these systems have wide range of advantages versus conventional treatment: lower capital costs, lower operation costs, use of chemicals is minimal; space for installation is much smaller, usage of chlorine for disinfection is minimal due to significant reduction of microorganisms; sludge production during the process is smaller due to smaller usage of chemicals, construction period is shorter due to smaller scope of works and relatively simply installation of membrane batteries.

In the scope of complex physical-chemical and biological water examination of Bocac water reservoir, the river Vrbas and trbutaries Ugar and Crna Rijeka, examination of standard microbiological indexes of water quality (aerobic organotrophs at 22-26 deg C and 37 deg C, total colliforms and colliforms of fecal origin) was performed during 2002 (March-November). Number of examined microbiological parameters was mainly in the scope of the 2nd water category (beta-mesosaprobic water) with worse water quality in upstream part of the reservoir. Ugar tributary had the best water quality, while Crna Rijeka had the worst status with obvious anthropogenic influence.

Slow sand filtration is an effective water treatment process. However, the performance of slow sand filters is influenced by the raw water turbidity. Filtration on pebble-matrix and roughing filters is introduced as a process effective in reduction of raw water turbidity. Efficiencies of these pretreatments documented on the raw water sources world-wide are presented in this paper as well as the investigation results from the similar raw water source in Serbia (Serbia&Montenegro).

Having known the fact that on the territory of West-Backa region the only water used for water supply system is subterranean water, from different water layers, an assumption can be made that the waters also differ in their physical and chemical content. It is also assumed that these waters differ in their total iron content. The aim of this work is to test the significance of the difference between central water supply systems of West-Backa region (Sombor, Apatin, Kula and Odzaci) for the value of iron in drinking water, using the adequate statistics methods. The central water supply systems in Sombor, Apatin, and Kula are using water from the second water layer (60-75 m), while the water supply system in Odzaci is using deep artesian and subartesian waters (146-220 m). Sombor and Apatin have the raw water purification system and one of the goals is to decrease the concentration of total amount of iron in drinking water.

In this paper, we present the results from both quantitative and qualitative composition of the Gastropod fauna from Lake Ohrid (profile HBZ-Radozda) with their vertical distribution in littoral and sublittoral region of the lake. The results of our investigations shows some changes in biodiversity and the density of gastropod communities that settle this profile, compared with the investigations made 30 years ago.

The area of Zidine is located southwest of Belgrade, Serbia&Montenegro, in the sanitary protection zone of the existing Belgrade water source. This potential water source is capable of yielding water of better quality than that of the existing raw groundwater, for final treatment plants at Bezanija and Banovo Brdo. In view of available capacities of these plants and the raw water system, the water disposal issue is practically resolved and the water source is also highly advantageous in economic terms. Two options of preliminary treatment after settling were considered: sand filters and microfilters.

During the period February 1999 - February 2000 samples of water taken monthly from the area before the outflow of river Crn Drim from the Lake Ohrid, in purpose of qualitative and quantitative investigation of phytoplankton community. During the period of investigation, the phytoplankton community was characterized by forms of Cyanophyta, Bacillariophyta, Chlorophyta, Chrysophyta, Pyrrophyta and Euglenophyta. Qualitative analysis indicated that algae of the division Chlorophyta and Bacillariophyta are dominant in the phytoplankton, while the results of the qualitative analysis showed that forms of Bacillariophyta are dominant. Seasonal dynamics of phytoplankton is characterized by autumnal and winter domination of Bacillariophyta, spring maximum of Chrysophyta and summer domination of Pyrrophyta. The total number of algae varied between 1500-95,700 ind/l in August and February 2000, respectively.