Environmental protection of urban riparian spaces increasingly demands approaches that go beyond technical and regulatory frameworks - yet the role of cumulative small-scale interventions in establishing standards for future large-scale transformation remains poorly understood. This paper asks: can student-led small-scale physical interventions and visual activism progressively build the spatial, pedagogical, and civic foundations necessary for environmentally responsible riverside transformation? A qualitative analysis of three interrelated student initiatives along the Vrbas River in Banja Luka was conducted, spanning nearly a decade: the Banjalučki mol (2017), a wooden riverside platform realised through an international student workshop; the Sewage Pipes Festival (2021), combining spatial mapping and an urban installation to expose river pollution caused by absent wastewater treatment infrastructure; and the "Vrbas is Neither a Construction Site - Nor a Trash Can" campaign (2025), producing seven visual interventions with civil society organisations in response to illegal riverbed construction. Each case was examined through process documentation, material outcomes, institutional responses, and patterns of community engagement. The Banjalučki mol revitalised a marginalised riverside location and demonstrated the public value of riparian space. The Sewage Pipes Festival initiated public debate on systemic ecological infrastructure. The 2025 campaign triggered inspection procedures and established civic monitoring as environmental advocacy. Small-scale experimental projects, developed through student pedagogy over time, function not only as independent acts of environmental protection but as preparation for - and implicit criteria governing - future large-scale riverside transformation.