The thesis here presented is about Environmental Policy Integration (EPI), one of the principal concepts in European Environmental Policy. It is assumed that EPI seeks to enhance the meaningful consideration of the environment in decision-making. Existing research on EPI only looks at sectoral environmental policy and the effectiveness of introducing its contents into other sectoral policies and it leaves out evaluating the physical outcome of societal and crosssectoral interactions. This thesis tries to overcome these shortcomings of existing research. It is argued that EPI seeks to change the way society relates to the environment. In order to improve EPI and its physical effectiveness the thesis starts out from the premise that we firstly need to better understand what and who shapes the physical environment in the EU. Secondly it is necessary to assess how these dynamics and decisions considered the environment, and what role this consideration played in shaping the environment.The work develops a framework based on critical realism and uses the strategic-relational approach. It reconstructs the interaction of actors with their contexts in relation to water use development, through a case study of physical environmental development, in the Algarve, from Portuguese accession to the EU in 1986 until the beginning of 2004. It answers the research question regarding what role the consideration of the environment played in water use development. In view of the answer it assesses where the environment was not meaningfully considered and why. Finally, it develops a brief set of recommendations.