Water is a basis for life and ecosystem health. And water, especially in regions affected by water scarcity, is a highly contested and politicised natural resource. The state-of-the-art in sustainable water resources management requires collaborative approaches that fosterthe integration of conflicting interests of multiple stakeholders. Achieving integration in complex and contested real life situations however remains a major challenge. Boundary work can facilitate thisambitious goal. This study evolves boundary work science to improve collaboration in the water sector. It develops a framework for boundary work that enables understanding, structuring and approaching barriers for collaborative water resources management. A case study from the Garden Route region, South Africa gives a grounded basis forthe conceptual developments and further provides in-depth insights into reasons and obstacles for collaborative water resources management in a contested local case. The case study serves both: An intrinsic analysis of a conflictive case, and conceptual developments to the boundary work framework - tested against local realities.