This paper presents the developments of a tool for integrated water management (Herramienta para el Manejo Integral del Agua – HERMANA). HERMANA combines; real-time meteorological, hydrological, and water quality data and forecasts; information from an institutional database; surface water and groundwater models; and, drought indicators based on satellite data into a web-based platform. Together, these tools provide the basis to plan for integrated, operational water management. To optimize the usability of these tools, we implemented an intensive co-design framework that consisted of developing a number of use cases in collaboration with the end user, the Corporación Autónoma Regional del Valle del Cauca (CVC). These use cases provide CVC with a step-wise approach to deal with a number of water management issues. Results show the impact that an integrated operational tool can have at a number of levels within the organization by making the water resources information accessible and visible in a tailored way. However, the largest hurdle is not the integration of data systems and models, which is usually technically feasible, but rather the sustainable implementation and integration into the decision-making process of a water management authority’s organization. Our co-design approach included numerous interviews and workshops with CVC’s staff to better understand the decision-making process within the organization, the requisite data and information, how the data and information are used, and how it can be presented in such a way that it facilitates decision-making processes. Outcomes from these discussions and a roadmap for future implementation are presented.