In a world that is becoming increasingly globalized and resource-limited, it is essential to support students' development of sophisticated reasoning skills when dealing with complex Earth systems. To address this need, we developed, implemented, and studied an introductory, interdisciplinary, 1-semester undergraduate course focused on socio-hydrologic systems. Here, we present results investigating undergraduate students' (n=92) socio-hydrological reasoning through the use of a pre-/post-course concept inventory and course assignment grounded in a real-world, regionally-relevant water quality issue. We found students' knowledge of core hydrology concepts increased significantly over the semester. Additionally, analysis of students' responses to a 5-item Quantitative Analysis of Socio-Scientific Reasoning (QuASSR) indicated a wide range of sophistication across and within the dimensions of SSR. A deductive analysis included the evaluation of students' responses to the QuASSR items using a rubric to evaluate the sophistication for each dimension of SSR (i.e., complexity, inquiry, perspective-taking, skepticism, and the affordances of science). Seventy-three % of students earned the maximum score for their perspective-taking responses by elaborating on two perspectives that might be taken by scenario stakeholders (ie: farmers and urban residents), whereas nearly half of students' skepticism responses failed to include reasoning as to how nitrate levels from the same site might be reported differently by scientists hired by different stakeholder groups. An inductive, thematic analysis was also employed to provide a richer account of the students' SSR. Students' offered a variety of ways that science could contribute to the resolution of this SSI, including by investigating problems, developing solutions, monitoring sites, and communicating knowledge. Here we provide evidence that using effective geoscience education approaches (ie: teaching content knowledge and overcoming misconceptions) coupled with socio-hydrological issues provide students with a productive context in which to develop water literacy.