The issue of water management as well as its impact on the community has been both a challenge and a concern of the European Union, which lead to adopting the Directive 2007/60/EC with the purpose of establishing a framework for the assessment and management of flood risks, by which the member states had to identify the areas for which they conclude that potential significant flood risk exist or likely to occur and to develop flood risk management plans and measures to reduce the consequences of flooding. In this respect, the Siret Water Basin Administration has declared the area of the Tazlău river, as a significant flood risk area (A.P.F.S.R.) (*** A.B.A Siret). The Tazlău River is a left-bank tributary to the Trotuș River, passing through the ten communes and partially through the outside the built-up areas of Onești city. Recent studies have shown the benefits of reservoirs and floodplains, as these provide the most effective way to buffer the effect of floods by slowing and spreading the discharge of a river (Băloi, 1980). By restoring and improving an existing lateral floodplain in the Tazlău River basin, in order to store part of the floodwaters that cause significant adverse consequences, will reduce the flood vulnerability of its crossings.