Agricultural policymakers are increasingly interested in the role of collective action to improve the effectiveness of natural resource management in rural areas. Analyses of socio-ecological systems highlight how distribution of benefits/cost is crucial for the success of cooperation among actors and hence it seems an element to take into account for the design of policies that focus on collective action. In this paper we use the Shapley value to ex-ante assess the distributional effect of collective conditionality constraints embedded in the policy, and their interaction with asymmetry in the access to the resource and with the social environment. We parameterise a model to a collective reservoir located in Emilia-Romagna (Italy), modelli...