Despite the commons being a site of conflict, the role of social movements in resource management has been under addressed. By exploring the role of environmental justice organizing during California’s groundwater reform process as a commoning practice, this article seeks to fill this gap and advance the understanding of how collective action can being leveraged to advance sustainable transitions. It argues that by challenging participation, scope, and authority, the movement has played a formative role in a landscape of enclosure. Applying a commoning lens highlights the important role of not only social movements in commons management but also of commons management as a venue for the rearticulation of socionatural relations. Such opportunities are particularly important in under institutionalized rural areas where opportunities to renegotiate these relations are often few and far between. To be fully understood, however, they need to be considered collectively as well as in context.