Integrated river basin management (IRBM) is an approach that has been interpreted in a number of different ways during the last 100 years. Current support for IRBM is based on a ‘myth’ of inter-agency co-ordination. However, increasing complexity and uncertainty in river basin systems has created ‘wicked’ or ‘messy’ land and water management problems. The limited capacity of state institutions to deal effectively with such conditions suggests that the current ‘myth’ must be reformed and that a more powerful system-response capability founded on inter-organisational collaboration should be developed. The case for a collaborative institutional approach to IRBM is examined with reference to the Fraser Basin Council in British Columbia, Canada.