Water is a limiting factor of agricultural production in an increasing number of regions. There is also ample empirical evidence to suggest that the economic value of agricultural landscape is substantial, which has been used to justify agricultural support programs in developed economies. We investigate the link between the environmental amenity of agricultural landscape and the value of water in crop production. We find that the environmental externality gives rise to a social derived demand for water which differs from the market‐based (private) derived demand for water. Policy implications regarding irrigation water allocation and pricing are drawn. An empirical example illustrates the methodology and main findings.