In order to divert the river, a small dam, called the upstream cofferdam was built upstream from the main construction area. This acted as a barrier to the river and caused it to flow through the diversion tunnels. Another cofferdam, called the downstream cofferdam was built downstream of the main dam site to prevent water flowing back into the construction area. Pumps were used to remove any excess water that seeped through the cofferdams into the construction site.

First Rocks officiated by Tan Sri Datuk (Dr.) Ahmad Tajuddin Chairman, Sime Engineering Services Berhad 2003

Concrete Faced Rockfill Dams require a footing or plinth to be constructed around their upstream edge. The plinth, built with reinforced concrete, serves as a foundation for the dam walls and floor.

Associated civil works such as the powerhouse, powwer tunnels, power intake and spillways were also built as essential structures of the hydroelectric scheme.

When the dam is completed the diversion tunnels will be closed and the reservoir will begin to fill; two of the diversion tunnels are then blocked off by the construction of a concrete plugs. The third contains a water releasse outlet so water can be released to provide continuous and controlled river water flow for downstream users of the dam during filling of the reservoir.