Natural ecosystems represented by the surface waters, which have developed during a long period prior to the human intervention, are replaced, modified and fragmented in a short period of time through dams, some linkage systems between the rivers through the old riverbeds and newly built channels and through the arrangement of the banks. In the water catchment area of the Danube, the effects of the major human intervention over the geographical area, especially over the large tributary rivers of this large stream, such as Argeș river, and also on most of the smaller running waters are harder and harder to monitor, to anticipate and to correct. The natural flowing regime of some tributary waters of the Danube has been considerably changed; thus, significant changes happen to the hydrological, physical-chemical and biological features of the waters through the emergence of some lake ecosystems, with a fragile balance. Important changes emerge at the level of some physical-chemical and biological qualitative indicators, such as: the turbidity, the dissolved oxygen content, the oxidation and mineralization of the organic material, malfunctions of some the self-cleaning processes, the accumulation of biogenic substances, eutrophication, the accumulation of mineral substances in the bed areas, the replacement of the river biocoenosis with a lake biocoenosis, the development of plankton, especially of the productive forms, the malfunction of the structure and dynamics of the fish fauna etc. The impact of human activity has a bad influence, in most of the cases, on the quality of the water in the dam lakes. The sustainable management of the water resources of these lakes, through the nearby urban and rural communities requires a knowledge of the environmental problems that are generated by the human impact and their removal or minimization.