Effective water management relies on integrating data from diverse sources, including both static and dynamic datasets. However, the challenge of data silos, especially in cities and agencies with disparate systems, has hindered progress in this domain. To address this issue, we introduce FOVDA (Federated Ontology View Data Access), an ontology-driven federated system designed to overcome data silos in the water domain. FOVDA enables seamless data integration and querying across heterogeneous data stores by leveraging a federated architecture and a domain-specific ontology. This system supports both local and global data interoperability, allowing agencies to exchange critical water-related data while maintaining data sovereignty. FOVDA’s federated query engine facilitates complex queries across distributed datasets, enabling decision-makers to access comprehensive insights for tasks such as water resource management, infrastructure resilience analysis, and disaster response. By bridging data silos, FOVDA empowers stakeholders with actionable insights, improving efficiency and collaboration in water management.