This research proposes to explore the possibilities of adapting Ostrom’s framework for analyzing common goods to a situation of cooperation in which experts manage the SASS (Tunisia-Algeria-Libya) cross-border basin. We propose a conceptual framework to analyze the role of experts in water governance based on two concepts: the concept of community of practice (CP) (Wenger, 1998) and the concept of polycentric governance stemming from the model (ADI: Institutional Analysis and Development) by E. Ostrom (2011). The use of the Delphi method based on the questioning several times by questionnaire of a panel of experts, aims to analyze both the agreements and the controversies. The Delphi survey first shows consensus between the 1st and the 3rd round around the evaluation of the irrigator’s behavior based on economic variables. Experts disagree on their recognition of the farmer’s responsibility for the state of the environment.