Current international and European Union environmental policies increasingly promote collaborative and participatory decision-making on appropriate and multiple governance levels as a means to attain more sustainable policies and a more effective and lasting policy implementation. The entailed shifts of geographical scale of governance can be exemplified by the EU Water Framework Directive in that higher-level policies are devolved not only to the member states but to local collaborative decision-making bodies on natural as opposed to territorial scales. To date, empirical evidence and theoretical considerations have remained ambiguous about the environmental outcomes of such modes of governance. At the same time, the relationship between multi-level governance and non-state actor involvement remains a largely uncharted terrain ...