This presentation is a case study that contributes to the conceptualisation of and methodology for studying the genesis of environmental concern and activism focussed upon a river as a nonhuman subject. It concentrates upon how some local villagers along the lower Kinabatangan River in Sabah, Malaysia, express their duty of care toward the river by their sustained local participation in assessing changing water quality in their wetlands and their sense of responsibility to foster care for the river among fellow villagers along the river. Making sense of this emergent duty of care entails examining not only how their local sense of place centres upon the river, but also how local communal and personal identity derives from this focus upon the river – peoples who inhabit this stretch of the river generically identify as Orang Sungei (River People). In analysing the importance of learning networks, trust and local agency to the development of social learning, this case study highlights the agency of those experiencing the process of socio-ecological change as a multi-dimensional concern. Their community participation in citizen science derives from their strong river-focussed sense of place and the care they express toward the river, which can be contextualised as a two-way interaction between society and ecology.