<p>Karst regions render groundwater both invisible and vulnerable, raising the question of how autonomy-supportive governance relates to community stewardship. Grounded in Self-Determination Theory, we examined whether Perceived Government Autonomy Support is associated with Public-Sphere Water Conservation Intentions indirectly via sequential associations with Autonomy Satisfaction and Intrinsic Motivation, and whether Self-Referencing conditions these associations. We conducted a cross-sectional survey in karst communities in Guangxi, China (<i>N</i> = 406) and estimated a moderated serial mediation model. Results showed a positive direct association between Perceived Government Autonomy Support and Public-Sphere Water Conservation Intentions and indirect associations through Autonomy Satisfaction and Intrinsic Motivation, consistent with the sequential path from Perceived Government Autonomy Support to Autonomy Satisfaction to Intrinsic Motivation to Public-Sphere Water Conservation Intentions. Self-Referencing positively moderated the association between Perceived Government Autonomy Support and Autonomy Satisfaction, such that the association was stronger at higher levels of Self-Referencing, and the corresponding conditional indirect associations through Autonomy Satisfactio, and through Autonomy Satisfaction followed by Intrinsic Motivation, increased with Self-Referencing. These findings extend Self-Determination Theory to the governance of invisible groundwater and&#xa0;suggest that Self-Referencing may function as a boundary condition for autonomy-supportive communication. Practically, although the cross-sectional design and the use of self-reported measures limit conclusions about sustained water-conservation practices, autonomy-supportive, person-centred communication that signals choice and respect and leverages locally resonant narratives may support community participation and help foster water stewardship intentions.</p>