Living organisms are an indispensable part of the natural habitat of watercourses and highly susceptible to the cause-effect relationship in the water cycle. The natural interconnection and interaction between living organisms and the watercourse environment calls for ecology to be incorporated into the system approach to international rivers so as to “provide the holistic management necessary for sustaining resources in a complex ecological/political landscape.” This approach shifts the legal focus from the physical reach of the river’s aquatic environment onto the biological components of a watershed. The geographical scope of international watercourses, therefore, does not extend so far as to include all natural forms of water in the hydrological cycle but remains within the confines of a self-contained hydrosystem. The legal emphasis is, rather, placed on the notion of ecology for an integrated environmental protection of the watercourse system. In this context, the ecosystem approach aims to bring ecological considerations into the domain of law