Rome is a complex metropolis. The city faces the challenge of imagining and shaping an inclusive and sustainable future for its inhabitants. On several occasions, city policies and interventions have not met the goal of preserving environmental resources. For their part, the inhabitants of Rome tend to doubt the ability of institutions to take care of the city’s resources. We focus on civic environmental monitoring led by the local independent association A Sud, aimed at assessing the environmental status of two of the city’s rivers. From a review of applicable literature on governance, environmental and social justice and climate urbanism, we build a theoretical frame to guide our analysis. We inquire how civic monitoring in a complex city can benefit urban resource governance and foster urban transitions. We also explore the extent to which these initiatives have the potential to inform or have actually informed the scientists and policymakers responsible for designing city adaptations. Our analysis demonstrates that citizen-gathered data can enrich the scientific knowledge base and trigger claims for interventions, bringing in information on local issues often overlooked by competent institutions. The initiatives also improved individual and collective attitudes towards the city and its resources, stimulating a sense of care and a watchful citizenship.