In autumn 1971, water pollution and poison incidents caused death in the Rhine. Aquatic life disappeared. The rulling opinion was: Clean up the waste water and life will return. It proved to be a half-truth. After treatment of waste water some organisms returned, others, particularly the migratory fish, did not. Barrages and weirs have decimated the migratory fish. Waste water gave only the final knock-out for these species. Slowly understanding arose for a harmonization between human interests and the ecosystem. In course of time the Rhine-states replaced the one-sided promotion of individual interests by the concept of integrated water management, a prerequisite for sustainable development. This contribution reflects the process of changing minds.