This paper studies the transformation of irrigated systems in the semi-arid Elqui Valley in Chile. We use the notion of hydrosocial territory to analyze the effects of new hydraulic infrastructures on irrigation practices and institutional water rules. The methodology is based on the collection and analysis of qualitative and quantitative data. The installation of new infrastructures associated with the rise of commercial agriculture, financed by the State, leads to a gradual abandonment of canals and water turns and disintegrates the collective decision-making process within the irrigators’ associations.