The Protection Action Plan for Merig-Ergenc Basin (2008) assesses the effects of development projects and economic activities on the environment, and provides for a short, medium and long-term action plan in terms of water resource management. There is also a land use plan for the Merfe-Ergenc basin. Water demand management measures in Bulgaria include water abstraction control. The Arda/Ardas has its source in the Rodopi Mountains (Bulgaria) and discharges into the Merig River. The Aterin-ska River is a tributary shared by Bulgaria and Greece.