The effectiveness and efficiency of environmental policy largely depends on how other policies take account of ecological objectives, whether in the industrial, agricultural, urban planning, transport, housing or budget sectors. The state bears responsibility for how these public policies interrelate, including establishing a hierarchy of priority or allowing one area to ignore another. What can we learn about environmental policy from an analysis of the tensions between multiple sectoral policies, and more generally about the state and the political and institutional functioning that shapes the management of an environmental issue? Taking water management in France as a case study, this article argues that an approach focused on the regulation of tensions between various public policies can shed new light on the structural difficulties of environmental policy. It shows how ideas, norms, interests, strategies, professional cultures, and so forth, that underpin public policy outside the environmental field shape the handling of ecological issues. It also highlights the way the state views and handles these tensions between policies through institutional arrangements and socio‐political compromises with influential sectoral actors and social groups.