Power Distribution in French River Basin Committees.

I study the distribution of voting power between di¤erent decision-makers in French river basin committees over the period 1987-2007. To do so, in the \u85rst part of the paper, I apply di¤erent power measures traditionally used in the literature as well as some other ones lesser known in this context. I compare then the predictions of several indices for the relative power of di¤erent decision-makers in di¤erent voting situations. In the second part, I describe the methodology to design an optimal decision rule. A simple computational exercise based on this methodology suggests that the residential water users in Adour-Garonne river basin were under represented in the river basin committee during 1989-2006. Key words: environmental management, water policy, collective decision-making, voting, power indices, optimal decision rule