To engage effectively with contemporary water-related challenges with scientific and social dimensions, students need to understand the properties of water and the nature of scientific processes and practices. However, students have difficulty in understanding core hydrologic concepts, and more work is needed to determine how they structure their decision making about socio-hydrological issues. In this study, the authors investigated undergraduate students’ decision making with a focus on the resources they leveraged to make and support their decisions about socio-hydrological issues.