The politics and practices of decision-making in a large dam project on the Greek island of Crete is investigated through the case study of the Aposelemis Dam, a European Union (EU)-funded development project to supply drinking water to three urban centers and major tourist destinations. Our study employs a modified version of the World Commission on Dams (WCD) evaluation framework. We compare the processes used in Greece with the best practices suggested by the WCD framework. Our study reveals three areas of weakness in this project. First, the political decision to build the dam took place in the absence of reliable hydrological studies and in the face of strong opposition from the residents, local governments, and professional organizations. Second, during the stages of planning, design, implementation, and operation of the project, the Greek government failed to follow transparent procedures in its deliberations. Affected residents and local governments in all the stages of the project were disregarded and mitigation of negative effects was negligible. And, third, the comprehensive sustainable regional development goals of the EU funding were never materialized.