“…Fourth, the paper applies some of these insights in the form of a case study on the geohistory of irrigation and ethnic politics in the Mayo Valley Irrigation District, in Northwest Mexico. Since the 1990s, Mexico has aggressivel y pursued a policy of ''decentral ized'' irrigation managemen t. But however much water governance became a centralized affair, it always depended on the capture and control of unstable hydraulic assemblages; that is, it relied upon mechanis ms that were ''ecologically embedded'' (Protevi, 2007 ), situated close to the earth, never too far from the places and people where water was applied. Floodplain irrigation, Butzer argues, is not a ''uniquely productive and predictable '' ecosystem (1996: 275).…”