Open Government Data (OGD) portals make data publicly available to promote transparency, innovation, and value creation. Although these data sets are available and used by a broad audience, little is known about how users engage with this data and the websites where they are hosted. The City of Cincinnati hosts an award-winning Open Government Data Portal and is used as a case study in this paper to understand the decision-making needs of OGD end-users. The portal allows users to access local data sets such as crime reports, permits and licenses, market analysis, education/research data, viewing public safety, and public health, as part of a local OGD initiative. To investigate users' social, economical, political and other decision-making needs, this study is conducted in two steps 1) a think-aloud activity, and 2) a design iteration combined with heuristic evaluation. Observing the use of the portal through this user study provided insights into user expectations as well as system and information requirements illustrated in design implications for OGD systems.