The relationship between iron content and turbidity in filter effluent and their effect on filter life are examined here. Also reported is the best method of obtaining continuous control of iron content.

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Phosphorous release from land to be inundated by creation of two water supply reservoirs: Rovni and Barje is determined. The aim was to define the cost effective degree of land clearance works before the inundation. Such works should guarantee the best protection, i.e. minimize the water quality deterioration after the reservoir body formation.The quantities of phosphorous which might be released from inundated land are determined on the basis of measurements of organic matter content being accumulated as trees and grass debris on the land surface, as well as in core samples of soil from the 10 and 20 cm depths. The kinetics of phosphorous release is determined on a laboratory scale, through the interaction of the samples with the river water within one month period. The amounts of possible total phosphorous to be released due to decay of the accumulated vegetation debris are estimated on the basis of the measurements at several locations with the results that the woodland contains 6000 g/sq.m and the meadows 600 g/sq.m. of organic matter, while in the arable land the organic matter content is considerably smaller.Accordingly the estimated amount of phosphorous release from the inundated land is 11,000 kg P for Rovni reservoir inundation, with 86 percent participation from woodland, 12 percent from meadows and 2 percent from other land-use patterns. For Barje reservoir, potential phosphorous release from the inundated land is estimated to be 7,000 kg P, with 98 percent participation from woodland, 1 percent from meadows and 1 percent from the rest of inundated land.The organic matters are, practically, absent from 10-20 cm depth of topsoil layer. The investigation of phosphorous release kinetics, on a laboratory scale, shows that its rate is within a range 0,004-0,008 gP/sq.m.day.Phosphorous load of the future reservoirs originating from the catchment area in the course of the average flow condition is 880 kg P/year from the Rovni catchment area of the total surface of 107 sq.km, and 1768 kg P/year from the Barje catchment area of the total surface of 236 sq.km. These quantities of total phosphorous are considerably smaller than those which might be released from the inundated land during the decay process even taking into account that it can last for several years.It is, therefore, recommended to remove all organic debris and 10-20 cm topsoil from the woodlands and meadows, in order to prevent deterioration of water quality in the newly created reservoirs, both from the point of view of the prevention of dissolved oxygen decrease and the increase of the nutrients.On an annual basis, most sediments act as a permanent sink for phosphate, although during summer the sediment usually acts as a temporal source for phosphate in the overlying water. The phosphate cycle in the sediment may be influenced by the addition of aluminum and iron hydroxides or calcium salt. To what extent these additions suppress the phosphate release from the sediment and enhance the annual

The study of the water quality of West Morava river basin was conducted with the aim of identifying the quality of the ambient water in the basin and determining the extent of pollution. Another objective of the study was to find the best feasible technical solutions and to estimate the costs of protection. Economically sound implementation plans for structural and non-structural measures for ambient water quality improvement are defined.

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