The case of Lima offers insight into the specific coordination challenges raised by nature conservation imperatives in a large Southern metropolis. Crystallized around water resource management, discussions about nature conservation link issues related to urban growth, environmental justice and the transformation of public-private relations. All the stakeholders share this diagnosis of vulnerability. Yet blame shifting strategies are proliferating, and controversies focus on the role of private actors, powers granted to local actors and the price of water. Against the backdrop of quick and visible transformations in other sectors, this chapter’s focus on water management conveys the importance of political and institutional dynamics in explaining resistance, conflicts and mobilisations of clashing interests. These are not directed towards technologies but rather issues of governance, understood as the collective capacity to agree, at the metropolitan level, on the hierarchy of priorities and the goals to pursue in an area with a precarious sectorial balance. In this classical debate between policy sectors, territories and politics, the frugality imperative is less of an end than a means. Contrary to analyses of the un-governability of large Southern metropolises, this chapter identifies three sources of increased policy coordination – through governance, privatization and the firm – contributing to the major overhaul of the water sector in the name of resource conservation.