The purpose of the works. The researches aimed to elucidate the composition and properties of sedimented matter from the water of Lake Ghidighici - a typical example of a eutrophic lake in the geographical area. Samples of mineral and organomineral sediments extracted from the lake bottom were investigated using for this purpose different chemical and physico-chemical research methods - elemental composition analysis, automatic acid-base titration, infrared and UV-VIS spectroscopy, Roentgen analysis, etc. The research was performed using the Metrohnom 848 Titrino plus titrator, Perkin Elmer Lamda 25 and Lomo SFD-46 spectrophotometers, Dron 3 diffractometer. Research results. Automatic acid-base titration of dispersed systems - solid particles from underwater sediments showed a relatively high buffer capacity for acidic agents and relatively low in the case of basic solutions. The separation of the fractions in the clearing processes were performed by subsequent agitation and sedimentation following the specificity of the sedimentation process over time of the fractions of the dispersed system. A total of seven fractions were separated. Acid-base titrations allow to evaluate the resistance capacity of the underwater sediment to the action of aggressive agents of acidic or basic nature. Knowing the laws of acid-base influence on underwater sediments allows the creation of stability conditions in the aquatic environment. Carrying out the clearing of water basins makes it possible to use underwater sediments as a material to strengthen the durability of soils against erosion and improve the physico-chemical and mechanical properties of soils. The phenomenon of cetyltrimethylammonium adsorption on underwater sediment particles demonstrates that the highest adsorption value has the fine fraction. The decrease of this characteristic is observed in the case of fractions with medium and coarse dispersion. The study of underwater sediments with modern physico-chemical methods allowed the identification in them of a series of minerals (silicates, alumosilicates, carbonates and others) characteristic of the soil in the area, their quantitative assessment and their role in nature, and the prospect of using their specific properties. The determination of the structural-sorbational characteristics and the surface chemistry of solid particles in underwater sediments prove the possibility of obtaining new filter materials and allow the development of original methods for purification of natural and wastewater, and the evaluation of acid-base durability and adsorbent properties of sludge develop soil fortification procedures against erosion processes.