The Rambakan Oya reservoir project is a multipurpose irrigation project which is commissioned to find a solution for the drinking water issue and irrigation problems in the area. It is the 10th zone of Mahaweli Development scheme and located bordering Badulla, Monaragala and Ampara districts.
There are archaeological evidences, those reveals about previous attempts to construct an irrigation tank here during the ancient time periods. According to them there are different legends and archaeological views on ancient construction of Rambakan Oya Reservoir. It is believed that construction of Rambaken Oya Reservoir was commenced by prince Giri Abaya who ruled the East, in third century, B.C. According to some other historical evidences it was commenced by Prince Saddhatissa (137-119 BC).
There is a one-mile longed old earthen dam can be seen, near to the newly constructed dam. It was constructed between Gorikanda and Galkanda with rip rap, in high quality. Around 250 feet long dressed stones made to use for the twin Barrel Sluice are still remaining in surrounding. Any way there is no evidence to prove that the construction was completed or the reservoir was functioned.
Near to the old Sluice, a stone slab inscription belonging to 12th – 13th centuries can be seen and which identified as Rambakan Oya Slab Inscription. It describes that the stone canal was built by Liyana Nayakayan and Kanathkan Vahanse, who lived in the Gal Weta area.
https://en.wikipedia.org/wiki/Rambakan_Oya_Dam