of large dams Massimo Amato**, Luigi Doria**, Luca Fantacci**, Guido Mazzà* , Massimo Meghella* International Symposium on Dams in the Societies of the 21st Century, 22nd International Congress on Large Dams (ICOLD) Barcellona, 18 Giugno 2006 **Università Bocconi, Milano *CESI RICERCA Addressing the social and environmental impact of large dams demands ever more comprehensive and integrated strategies, well beyond material and technical interventions. Within this broadening scope of action, a crucial role is played by policies designed to enhance communication, participation and stakeholders’ involvement. In this perspective, two fundamental needs emerge: to develop methods of classification, analysis and evaluation for the assessment of large dams environmental and social management actions; to exploit the opportunities coming from the evolution of certification schemes for Environmental Management Systems (EMS) and from their application to large dams. This paper focuses on the most relevant trends in the approaches developed to deal with the problems outlined above, with particular reference to Italian best practices. The first part presents an integrated evaluation scheme for social and environmental impact management actions. The scheme aims at a quantitative assessment of monetary compensations, mandatory and voluntary stream flows, and other actions, ranging from reduction of landscape impact to local development policies and stakeholder management. This activity was developed thanks to the support of the public funded research framework programmes for the Italian electric system. The second part investigates the possible use of voluntary environmental certification (according to European EMAS regulation and ISO14000 international norms) as guidelines for the development of integrated management systems for the assessment and containment of large dams social and environmental impact. Concluding remarks are dedicated to the broader issue of water allocation. The debate on the socio- economic impact of large dams gives dramatic evidence to the specific feature of water as a resource: unlike other staple commodities or raw materials, water is not only scarce but largely not substitutable in its most essential uses. This characteristic brings up the question of water allocation and the need to develop specific distributive instruments, necessarily differing from traditional market mechanisms, and possibly akin to clearing systems developed for other public goods (e.g. emission rights).