Our aim in this paper is to assess the effects of water quality protection policy on agriculture. We focus on the case of Vittel (France) which is seen as an example by scientists and policy makers. Since the beginning of the nineties, a food-processing company has engaged different actions to stop nitrate pollution on the catchment area of Vittel-Contrex, in order to maintain the production of mineral water. Their main actions have been to buy agricultural land, on the one hand, and to contract with farmers which are volunteer to adopt environment-friendly practices, on the other. We made a sociological survey, based on comprehensive interviews, to analyze the firm’s strategy of land purchase and its impacts on local agriculture. We put our attention on farmers’ professional dynamics on this territory. To conclude, we underline the limits of industrial stakeholders’ intervention on the ecologization of agriculture.