Integrated water resource management is a process oriented towards sustainable development through the shaping, allocation and monitoring of water resources, taking into account social, economic and environmental objectives. The water management policy realised in Poland is based on the idea of sustainable development and requires the use of application of appropriate evaluation tools in the process of socialised decision-making concerning the initiation and realisation of investments with an impact on water management. This study discusses methods of assessment of planned investments, such as: cost and benefit analysis, environmental impact assessment. These are balanced against the method recommended by the World Commission on Dams – A New Framework for Decision-Making,as well as the main guidelines of the Positional Analysis (PA) method based on Ecological Economics. The latter opposes Neoclassical Economics, as well as Environmental and Natural Resources Economics. Integrated water resource management is a philosophy that informs that the attitude that considers the balanced shaping of water resources as the most important objective of managerial activities. Those responsible for the decision making are obliged to take into consideration the wider context that accompanies such a process. They search for and invite many stakeholders to participate in the decision making process, creating or utilising the platforms for exchanging often opposing opinions that are present in democratic societies. In such activities, the multi-criteria assessment may be a useful instrument, taking into consideration the coincidence of many, often equivalent, objectives, and utilising the multi-element set of selection criteria. The paper emphasizes the functional values of the multi-criteria evaluation model for an investment, which is based on the sustainable development objectives.