Man-made lakes cause direct and indirect changes in environmental conditions downstream of the water reservoir. Management must consider these water quality and environmental effects as well as uses of the river below the water reservoir.

The results of the examination point out on heterogenity of the phytoplankton community. The presence of 212 taxa has been noted. In the way of quality the green algae are dominant. In all the aspects of the quantitative analysis the domination of Bacillariophyta has been noted, first of all the centric forms. The amount of nutrients on the locality of border with Hungary is considerable, thus during low water and high temperature, the intensive algae development is usual.

Aspiration to multipurpose use of built drainage systems structure in Vojvodina, total length about 20,000 km, must be followed by detailed investigation of influence of water stream through detailed canal network (DCN) from water source to the final consumer. Typical cases of two purpose use of DCN is supply canal of drainage / irrigation system on region Middle Banat, Zrenjanin, characterized by taking water from Begej river and long stream to the final consumer. Influence of long stream through DCN to water quality change are investigated on mentioned localities during 2004. Obtained results are pointed out water quality decrease in these conditions. Decrease is expressive in case of smaller flow. This paper deals with estimation of water suitability for irrigation taking into consideration possible undersirable effects of this water to irrigated soil.

The river Crnojevica is a subject of lasting manny years physicochemical and microbiological investigations, which show worring pollutants presence into the water current. This work represent preliminary investigations of Crnojevica river water algal flora (phytoplankton and phytoperiphyton), carrying out over summer period of 2004. Aim of the investigation was to point, based on algal analysis, as reliable indicators of water quality and ecological status of an aquatorius, the need to protect the river from permanent communal and industrial waste water pollution. The hyperproduction of phytoplankton in the investigation period was stated, but it varys along the current, in accordance with efluent inflow. On the base of saprobiological analysis of phytoplankton, determinated water quality was in class 2, till the worse was noted at T2 measure place, on the inflow place of Rijeka Crnojevica settlements sewage.

Eutrophication is one of the main problems of water deterioration in accumulation lakes. Phosphorus is considered as the key factor for eutrophication of lacustrine water. Its concentration in lakes originates from external input and the emission from the sediment. It was necessary to determine the substrates of phosphorus by sequential extraction in order to determine the dynamics and bioavailability of phosphorus. On the basis of results obtained the proposals for the preparation of land were made in order to minimise the input of phosphorus.

Potentiometric stripping analysis (PSA) is highly sensitive electroanalytical method for determination of traces of heavy metals. In this paper detection limit and linearity of potentiometric stripping analysis for lead was investigated. Method was successfully used for determination of traces of lead ion (detection limit 5 microgram/cubic dm) in stream water of river Ibar, before and after joint of potential pollutant.

In the frame of the project Revitalization of the Big DTD Canal and preparation for introducing modern wastewater treatment plants for the towns and industry in the Backa region, an all-inclusive program has been prepared for monitoring quality and quantity of water in the Big Canal and pertaining lateral canals. The paper presents results obtained for contents of nutrients (N and P) that indicate a poor quality of the Canal water, especially in the segment from the triangle to the hydrological node Vrbas. In many cases, measured concentrations of nitrogen and phosphorus were several times higher than maximal tolerable levels, so that it is necessary to undertake urgent measures with the aim of preventing further degradation of the Canal water, and eventually its revitalization.

During several years of hydrobiological investigation of the Zapadna Morava river the Medjuvrsje and Stancici localities stood out; the most favourable water quality was registered with the Medjuvrsje reservoir (being constantly of the class 2), whilst, according to all the data obtained over the years, water quality of the Zapadna Morava at Stancici locality was the worts. The Medjuvrsje reservoir is in stable eutrophic phase. The saprobic index value points to a certain water quality improvement. Floristic diversity in the locality of Stancici increased over the years. An increase in the percental share of the oligosaprobity indicator indicates a certain organic load decrease and an improving water quality trend was recorded as indicated by lower saprobic index values.

Water samples for chemical and microbiological analyses as well as material of the water community to be considered in the assessment of qualitative and quantitative composition of phyto- and zooplankton, and bottom fauna were take on 30 May 2001 at two profiles. Judging by the most of the analyzed chemical parameters, with the exception of BOD5 and oxygen saturation values indicating class 2, water of the Bovan lake accumulation belongs to the 1st class of water quality. According to the presence of heterotrophic bacteria, water was characterized as class 1-2 (after Kohl). Also, 6 groups of phyto- and 4 groups of zooplankton were recorded. Relative abundance and qualitative composition values of plankton show that saprobic index ranged from 1.54 to 1.98 pointing out oligo-beta, namely beta-mesosaprobic character of the accumulation. Saprobic index when oligochaetes were considered amounted up to 3.6 (alfa-mesosaprobic water).

In this paper, there were discussed the results of ecological investigation of the Montenerin part of the Adriatic sea during the period 1996-2003. Evaluation of the sea-water quality was done in the coastal sea. The importance of multiannual ecological investigations was emphasized, too.