While the importance of flow variability in water treaties is acknowledged, little work has been done to identify those mechanisms that have actually been employed. The present study uses a content analysis of a large number of water treaties in order to identify approaches used in practice. It was found that flow variability has been governed using a variety of mechanisms. While some mechanisms explicitly address variability, the majority use more subtle, open-ended approaches. Most of the mechanisms adopted deviate from an “ideal” state of being both flexible in the face of change but binding in enforcement. Instead, they reflect trade-offs between flexibility and enforcement. These results are used to discuss the advantages and disadvantages of particular variability management strategies.