Sustainability appraisals produce evidence for how well water governance regimes operate and where problems exist. This evidence is particularly relevant for regions that face water scarcity and conflicts. In this study, we present a criteria-based and participatory sustainability appraisal of water governance in a region with such characteristics—the dry tropics of NW Costa Rica. Data collection included 47 interviews and three stakeholder workshops. The appraisal was conducted through a collaborative and iterative process between researchers and stakeholders. Out of the 25 sustainability criteria used, seven posed a significant challenge for the governance regime. We found challenges faced by the governance regime primarily clustered around and were re-enforced by failing coordination related to the use, management, and protection of groundwater resources; and inadequate leadership to identify collective goals and to constructively deliberate alternative ways of governing water with diverse groups. The appraisal yielded some positive impact in the study area, yet we found its application provided only limited strategic information to support broader problem-solving efforts. Insights from this study suggest key starting points for sustainable water governance in the Central American dry tropics, including investing in increasingly influential collective organizations that are already active in water governance; and leveraging policy windows that can be used to build confidence and disperse more governing authority to regional and local governing actors that are in-tune with the challenges faced in the dry tropics. We conclude the article with reflections on how to produce research results that are actionable for sustainable water governance.