The world’s rivers are in ecological decline. They are the most threatened of all freshwater habitats, and threats to their ecological integrity are both increasing and compounding. Rivers are crucial for supporting biological diversity (being unusually biodiverse habitats) and are key to the function of the Earth system. Rivers are also critical for supporting people. They provide food, water for drinking and irrigation, and a significant proportion of the world’s energy. Additionally, people value rivers for their heritage, and the opportunities they provide for aesthetic appreciation and recreation. Rivers also form key components of cosmologies and spiritual practices, and indigenous ways of living and being. These ‘cultural’ values associated with rivers are the focus of this study. Laws which govern the use and conservation of rivers are generally concerned with safeguarding the socio-economic benefits generated by their utilization. Heritage, aesthetic and recreation interests are recognized to a lesser extent. Each of these provides their own justifications for and approaches to the ecological conservation of rivers. However, the potential role of cultural values (spiritual and indigenous values) in improving ecological outcomes for rivers is underexplored. In this study, I examine the recognition of cultural values associated with rivers in water laws at the international, regional and domestic levels. I ask the question: would greater recognition and implementation of cultural values in water laws improve ecological outcomes for rivers? I find that the cultural values associated with rivers are heterogeneous and highly context-specific. Their capacity to enhance ecological conservation of rivers is variable. However, some cultural values show real promise in their ability to improve ecological outcomes. I argue that these values should be recognized and implemented in water laws at the domestic, regional and international levels.