The Samanala Dam is a dam primarily used for hydroelectric power generation in Sri Lanka. Commissioned in 1992, the Samanalawewa Project is the second-largest hydroelectric scheme in the country, producing 405 GWh of energy annually. It was built with financial support from Japan and the United Kingdom. It is notable for a large leak on its right bank. Power production continues as planned despite the leakage, and the water from the leak now provides two thirds of the water issued by the reservoir for agriculture in downstream areas.LocationThe Samanala Dam is located in the Uda Walawe basin. It was built at the confluence of the Walawe river and the Belihul Oya, a location 400m above mean sea level. It is near the town of Balangoda and 160km southeast of Colombo, the capital. The ground of the project area is karstic.Background and developmentWith the Mahaweli and Laxapana hydroelectric power projects implemented, the demand for electricity in Sri Lanka rapidly increased. When it became clear that it would not be possible to meet the demand with coal-fired power plants, the government of Sri Lanka decided to initiate another hydroelectric power project. A reservoir type hydroelectric power plant was planned to be constructed across the Walawe river, which would address the shortage of electricity in the country. Detailed investigations for a hydroelectric power plant in this area have been carried out since 1958, but the scheme was initiated only in 1986. The financing for the project was given by the governments of Japan and the United Kingdom.