While the citizen science approach has gained prominence in water and ecosystem services management, methodological limitations, insufficient resources invested in monitoring practices and a lack of effective mechanisms for integrating the approach into existing monitoring and decision making processes means that its full potential has yet to be realized. Nevertheless, the concept offers a real opportunity to address data gaps and assist decision makers operating under a wide range of socio-ecological and environmental uncertainties. In this paper, we report findings from a project in which low-cost sensors were deployed to collect hydrological data in two study locations in Nepal. We found evidence that the citizen science has potential to generate locally relevant data and knowledge which can enrich a much more polycentric governance of water ecosystem services management. However, some major challenges need to be overcome, in particular developing locally-tailored monitoring sensors, standardizing monitoring and data sharing practice, improving local capabilities to collect quality data and making the approach more sustainable and adaptive to emerging environmental threats and uncertainties. If sufficient attention can be given to these key challenges, citizen science looks set to play a significant future role in water and ecosystem services management.