The aim of the project was to study in detail the sorption mechanism of hazardous (Hg, Cd, Pb, Cr, Cu, and Ni) and some other (Zn, Mn a Fe) heavy metals in sediments, the binding strength, and the conditions under which the sediments serve as source or accumulator of heavy metals. In the first part the results served for comparison of heavy metals contamination levels in selected southern Bohemian water reservoirs (the ponds Bezdrev, Naděje, and water supply reservoir Římov). From the above, the Římov reservoir exhibited the most severe sediment load by heavy metals, in particular by Cd, Hg, Cr, Ni, V, Cu, Pb, and Be. The second part of the project was aimed to select the optimal extraction method of interstitial water from the sediments; the sediment centrifugation in the laboratory was found to be the best suitable. Concentrations of all ions in this water were by order of magnitude greater than in the water from the reservoir. Use of interstitial water as reservoir load indicator showed to be very disputable. The third part of the project evaluated influence of selected factors on the release of hazardous heavy metals from the sediment to the water. It was proven that even a small change in pH values changed substantially the sorption of the metals under study and thus their concentration. Probably the most sensitive to pH value changes is the sorption of Hg, which is released already at a very weak alkaline reaction (liming). The fourth part of the results helped to clarify the type and strength of hazardous metals binding to the sediment, and to assess the real risk of their release from the contaminated sediments. It is also possible to explain their behaviour in the water reservoir sediments based on the knowledge of the individual elements fractions. The best suitable element for this approach is the Mn, which mostly binds to the ion exchange fraction, being released most readily, and in alkaline environment forms a purely soluble manganese hydroxide. Therefore the Mn concentration varies considerably in the surface water, as the pH value oscillates around the neutral value. The results will be used for revitalisation measures evaluation in water reservoirs.