The Bakun Dam in the Belaga district may begin to generate 300 megawatts (MW) of electricity in June next year with the impoundment having started today, said Sarawak Hidro Sdn Bhd managing director Zulkifle Osman.

He said the diversion tunnel gates were closed at 10 this morning and the flooding would take about seven months to reach the minimum operation elevation of 195 meters (above sea level) to run the wet-test of the turbine.

"We are expecting the first commissioning one month after the wet-test of the turbine - June 2011. The first turbine will produce 300MW of electricity,” he told Bernama when contacted today.

Sarawak Hidro, a wholly-owned subsidiary of the Ministry of Finance Incorporated, is the developer of the Bakun Dam, which will generate 2,400MW of electricity when all the eight turbines are in place by 2012.

The area to be flooded covers 69,500 hectares of land, an area equal to the size of Singapore.

bakun dam location map The Bakun Dam, the world's second tallest concrete rock-filled dam, is located on Balui River in the upper Rejang River basin, 37km upstream from Belaga.

The dam is expected to be completed by December. The overall cost of Bakun has been put at RM7.3 billion, but due to cost overruns, compensation for delays and interests, the final cost is said to have escalated.

Meanwhile, on the safety measures and precautions during the impoundment, Sarawak Hidro, in a statement, said the public and river users are reminded that entry to the immediate downstream area of the spillway plunge pool would be totally prohibited and big warning signboardS have been installed to alert the public.

It said water release from the spillway is necessary in the event of flooding to ensure safety of the Bakun Dam and surrounding areas.

"Sarawak Hidro will work closely with Sarawak River Board and Sarawak Department of Irrigation and Drainage to notify the public and river users," it said.

Special precautions

For those traveling within the Bakun reservoir in the future, Sarawak Hidro said special precautions should be taken to ensure that boats are designed to suit the altered condition whereby stronger winds and waves are anticipated at times due to the large water body.

"Appropriate safety gears have to be on board and life jacket is required for the safety of the users. Sarawak Hidro will provide a boat-landing platform near the dam site for reservoir users," it said.

During the impoundment, Sarawak Hidro said the flow downstream of the dam would be maintained through a mechanism to release between 150 and 260 cu-m per second of water depending on the reservoir level from the water release outlet to maintain the minimum base flow in the river.

Hence, reduction in the downstream water level is envisaged.

"It should be pointed out that river transportation by express boat from Kapit to upstream which is presently interrupted during the dry season would be possible all year round when water release from Bakun spillway commences and when the project is fully operational.

"Regular water release through the spillway will increase the downstream water level to aid navigation in Batang Rajang between Kapit and Belaga," it said.

During normal operation after impoundment, it said the release of flow through the power generation would improve the water quality as water would be tapped from the top 10m to 15m layer which is of good quality to run the turbines.

“Water fluctuation in the river will be regulated and controlled resulting in improved navigation and reduction in bank erosion and sediment transport benefitting the downstream settlements,” it said.