Institutional obstacles to integrated water management at the river basin scale have been discussed in detail in the water governance literature, but there has been less attention to the development of analytical framework for understanding local government cooperation. In this study, a median voter model was developed to describe the political processes by which municipalities lend their support to land-use control in river basin management planning. Relative income, population growth, and land cover data — as measured at municipality level — are advanced to be the main determinants of municipalities׳ positioning on additional environmental zoning. The consultation process for the SAGE (planning and water management scheme) for the Gironde estuary and associated areas was used as a case study. Spatial logit estimation of the determinants of the results of voting in this consultation process suggests that municipalities׳ decisions are strongly influenced by the landscape preferences of the median voter. Acceptance of the SAGE project is an increasing function of relative income and population growth, as measured at municipality level. Furthermore, the municipalities that reject it are mainly those with the largest agricultural areas. The results confirm the existence of a very strong political component in the process by which a municipality decides whether or not to support a river basin plan. This decision can be linked to the preservation of natural landscape amenities in peripheral areas, while elsewhere it is connected to the protection of farming. Theoretical and empirical developments of political economy analysis provide an alternative framework by which to understand institutional fits and interplay in water resource management