Cooperation between countries or regions that share a political border is one of the primary concerns of border studies. However, while cooperation between states is a well-established field based on international agreements, the cooperation between internal-state regions is not as well understood and requires more exhaustive study. Cooperation agreements between regions are frequently based on the shared and collaborative management of environmental resources such as river basins. This paper aimed to identify mechanisms of river basin cooperation in the internal border area between Catalonia, Aragon and the Valencian Community (Spain), with the objective of analyzing dysfunctions in their water management and identifying the territorial needs for the efficient management of these resources. Focus group sessions were conducted with 84 public administration stakeholders and a total of 53 border municipalities were involved in the project. In our study area, we identified a considerable number of dysfunctions that affected different levels of water management (e.g., supply, navigation and reservoirs) and which impeded effective cooperation between different administrations (above all, between town councils and the public water agencies). However, we also identified several interesting initiatives to promote water management in both the medium and long term, including river contracts, river commonwealths and river tourism projects managed by border municipalities.
