This is a rock filled dam which is constructed across the Kotmala Oya at Kadadora. That dam is 87m in height and it is 600m long. The construction work had begun at 1979 and the construction works of the reservoir was officially completed and started generating the electricity on 1985. This was a project which was carried out as a sub project under the rapid Mahaweli Development Project. The financial aid was provided by the Sweden.
Kotmala Oya is a branch river of the Mahaweli River. This dam has being constructed about 6.5 km upper to the place where Kotmala Oya meets the Mahaweli River.
The main objective of constructing this dam was to generate hydropower. The power station is an underground one which is located at Atabage Mountain. It has the capability of generating about 67 MW of power to the national grid.
The nearest town is Ulapane and you can reach this dam by using the Ulapane – Pussellawa road. There is about 10 km to this dam from the Ulapane town.
A large number of people (about 3000) lose their living places due to this project. They were moved to alternative areas in the country. In addition to that there were many temples sunk in the reservoir. Mahaweli maha seya is a new pagoda which was built in a memory of those temples.