The overall purpose of this study was to assess the knowledge that students have about the ecosystem concept of rivers and their sustainable management. A survey of nine questions gathered responses from 3447 students at three different Spanish education levels (Primary, Secondary, and bachelor’s degree in Primary Education) and six different geographic territories in the Iberian Peninsula. Respondents showed a limited understanding of rivers, much simpler than the ecosystem concept, which was related to proposals of unsustainable management of these ecosystems. Although the results were analogous among territories, undergraduate students had a more complex concept of rivers as well as more sustainable ideas regarding their management compared with Primary and Secondary Education students. This study demonstrates the lack of knowledge transfer between science and students regarding river ecosystems. Current educational programs should be adapted to address, even at early stages of education, the sustainability challenges around river ecosystems.