The fees and access costs paid by farmers do not reflect the private value of water for farmers, especially in times of stress on the resource. This tension increased by the effects of climate change makes it necessary and urgent to reconsider the implicit value of irrigation water. To this end, we mobilize the AROPAj agro-economic model by dealing with the problem of a limited water resource required by several farms. Based on a theoretical relationship associated with the model and characterizing the implicit value of water, we estimate a shadow price that operates for each of the irrigated crops in all the irrigating farms of a region. This case study covers all French metropolitan regions. When water availability covers half of farmers’ 2016 unconstrained demand, the water shadow price increases up to 1.64€/. The impact on production systems strongly depends on their geographical location, with the prospect of regional crop specialization.
