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.

Complex hydrodynamics and thermal regimes of temperate lakes have a major impact on temporal and spatial distributions of water quality indices. Transport processes in lakes are driven primarily by external forces such as wind and solar radiation but also depend on the inflow and outflow regimes. This paper presents a simplified ID model developed to calculate seasonal variations in vertical distributions of temperature and dissolved oxygen in Lake Zavoj in southern Serbia. Model results that were based on monthly averaged meteorological data are in good agreement with measured vertical profiles of temperature and dissolved oxygen. The simplified model is an efficient tool for long-term prediction of water quality indices in deep, medium and long residence time lakes.

Zooplankton community analysis was conducted for spring (April - 07) and summer (August - 07) in Boka Kotorska Bay. Analyses included determination of biomass and qualitative composition. Data are given on the number of specimens per cubic meter as well as on the volume organisms. Qualitative composition showed domination Copepoda of zooplanktons groups.

During the summer 2009 physical, chemical, biochemical and bacteriological analyses of water of rivers Mušnica and Suški Potok were performed. Microbiological analysis point out that waters belong to the 2nd class by Kohl. The river Mušnica had slightly polluted water, and river Suški Potok had very slightly polluted water. According to the Regulation on Classification of Surface Waters in Republic of Srpska (Bosnia and Herzegivina) all the observed parameters belong to the first or second water quality class. Only the stream Suški Potok has chloride concentration that exceeds a third-class quality. On the basis of observed characteritics it can be concluded that Mušnica and Suški Potok have a satisfactory water quality.