Legal Resilience at the EU / non-EU Interface: Best-Effort Cooperation in Transboundary Lakes

Climate change is reshaping hydrological regimes in European transboundary lakes, intensifying pollution pressures and exposing the limits of existing coordination arrangements. Hydrological extremes increasingly interact with persistent and emerging pollutants, creating compound challenges for legal and institutional frameworks developed under more stable conditions. While resilience has become a central concept in water governance research, we still know comparatively little about how specific legal designs support adaptive capacity across borders.

This paper draws on empirical research from a Swiss National Science Foundation–funded project on transboundary water cooperation in Europe. It examines pollution governance in three transboundary lakes—Lac Léman (France–Switzerland), Lake Lugano, and Lake Maggiore (Switzerland–Italy)—where cooperation duties are often framed in flexible or “best-effort” terms and where EU and non-EU legal orders meet. The analysis compares bilateral agreements, joint commissions, regulatory standards, and coordination practices across the three basins.

The empirical material is analyzed through the lens of legal resilience and adaptive capacity, building on work by Ruhl and by Cosens and Soininen. Five systemic properties—reliability, efficiency, scalability, modularity, and evolvability—are used to assess how legal arrangements facilitate coordination under conditions of uncertainty. The paper questions whether, under certain conditions, flexible legal arrangements (such as best effort obligations) can function as enabling elements of systemic resilience in transboundary water governance, allowing incremental adjustment and locally adapted responses to emerging pollutants and hydrological extremes. We conclude by deriving design implications for transboundary lake agreements facing compound hydrological-pollution pressures.