Claim: Ivaylovgrad located in the eastern Rhodope Mountains and is situated on the Arda river, Southern Bulgaria is a hydroelectric power plant (HPP) is the last stage of the Arda cascade but the initial plans for the construction of a dam on the Arda date to as early as 1948.
Evidence: Ivaylovgrad (Bulgarian: Ивайловград, "city of Ivaylo") is a town in Haskovo Province in the south of Bulgaria set near the river Arda in the easternmost part of the Rhodope Mountains, and is the administrative centre of the homonymous Ivaylovgrad Municipality.