In the present work are revealed the results of the multi-annual researches on the dynamics of the hydrochemical indexes (salinity, main ions, nutritive elements, trace elements, suspended matter etc.) in the Dniester river. The results of the field and experimental researches show that the content and the dynamics of the majority of the indexes are acceptable and rather favorable for the development of the hydrobionts. Only in less than 2% of the cases the concentration of some metals, can negatively influence upon the production – destruction processes and the development of the hydrobionts in the Dniester river.The accomplished researches showed that according to the content of the dissolved oxygen the Dniester river water is acceptable and rather favorable for the development of the hydrobionts. The content of the dissolved oxygen was varying between the limits 6.8-10.6 mg/l, that correspond to the water saturation equal to 68-114%. The concentration of the main ions as well as the degree of water salinity increase continuously downstream the river. The comparison between the data from 2005-2009 and the existent materials from 1993-1996 indicate an insignificant growth of the chlorates and sulfates concentrations, but the total salinity value generally corresponds to the one from 1996.One of the most important indexes of the water quality is the content of the nutritive and trace elements. We have to mention that the level of nutritive element concentration at present is similar, the concentrations of the nitrates, nitrites, cooper, and zinc, are slightly lower, in comparison with 1993-1996. The building of hydropower stations in Ukraine (HPS-1, HPS-2 and HAPS) and constructions on the Dniester river have negative impact on the river ecosystems:impairment of river hydrological regime.  the river is covering with water plants.impairment of natural dynamics and processes of migration of chemical elements in the system «water-suspended matter- sediments».the processes of secondary pollution of water were intensified.the riverine species of hydrobionts are replaced with lacustric species.