I employ different concepts of voting power to analyze how the composition of environmental committees and voting rules relate to the voting power of different decision makers in different voting situations. I demonstrate the use of the concepts on data for French river basin committees over the period 1987-2007. In the second part of the paper I discuss how the existing tools and methods can be adapted to examine the problem of fair representation of different interests within environmental committees. The analysis brings relevant insights to the recent water policy debates in France.