Transboundary watershed management seeks to reconcile the dichotomy between political lines and the resources that flow freely over such borders. Transboundary waters cover half of the earth’s surface and define the natural communities of over 40% of the global population. Because water plays an integral role in every culture and society, international entities seek to identify the principles and methods that minimize conflict and maximize harmonious water resource management across borders. Successful management practices to date have aimed to incorporate relevant scientific literature throughout the basin using alternate governance structures. International River Basin Organizations (IRBOs), independent governing structures, provide one such method of governance along shared water bodies. In order to determine how science influences policy and management in IRBOs, this research examines five case studies across three IRBOs: The International Joint Commission, the International Commission for the Protection of the Danube and the Mekong River Commission. To understand the gap between science production and its incorporation into IRBO policies, we conducted a comprehensive literature review and applied the findings from existing scientific literature to understand science-policy process in the five case studies. Within each case study we traced the story of science production and its uptake into policy by highlighting two types of key information in the process: the role of mandates and IRBO structure, and the IRBO’s relationship with relevant actors. Through this process we identified and explored the gap between science production and policy action, demonstrating which mechanisms are essential for generating policy founded on scientific research.