In a context of uncertainty linked to the ecological transition, the issue of managing the scarcity of natural resources has become an essential factor in the study of environmental policy (Markard, Raven, ruffer, 2012; Lubell, 2013; Hornberger, Hess, Gilligan, 2015). Faced with the collective ideals of the “governance of the commons,” (Ostrom, 1990; Ingold, 2008) crisis situations are particularly revealing of ongoing changes (Bakker, 2010; Barraqué, 2011; Lascoumes, 2012). From this point of view, the drought that has affected the American Southwest for the last fifteen years illustrates the difficulties encountered in terms of regulating the environmental impact of human activities (Lynn-Ingram, Malamud-Roam, 2013). Tis chapter aims to examine the implementation of ecological measures in water policies which, traditionally, have been subordinated to the imperatives of the region’s economic development (Worster, 1985; Reisner, 1986; Pincetl, 2011).