The new Peruvian Water Law (2009) inaugurated a transition phase in the country's water governance model, in theory changing the power relations among the actors involved in the decision-making process. Formerly excluded actors were invited to participate and bring their particular views into multistakeholder spaces. While this diversity of actors, informed by different types of knowledge, has been highlighted as an attribute of more adaptive systems, it does not necessarily lead to a real change in the constellation of power. The case of Arequipa illustrates this shift towards a new water governance system, with the creation of a river basin council based on a prior (and exceptional) example of informal multi-stakeholder water management. Yet the growing participation of a large mining company in financing water-related infrastructure, and its alliances with other actors, might challenge the potential of the new participatory body to represent equally the interests and views of all its members, and therefore to question the existing norms to bring about transformative change. (1)