Vientiane Times, 1 July 2013

Mega First Corporation Berhad (MFCB) is proposing a single dam across the Hou Sahong River, about 130 metres upstream of the Xang Pheuak junction in southernmost Champassak province, the company announced last week.

The firm has no concession agreement yet with the Lao government to operate a hydropower plant at Don Sahong, so there has been no civil engineering construction at the site, the company said.

Environmental Manager of the Don Sahong Hydro Power Project, Dr Peter Hawkins, said in the company’s statement that water level and bathymetry measurements and drilling work have all been done to optimise the project design.

“In addition, because we are well aware of the potential environmental and social impacts of a dam on the Hou Sahong, we have been trialling measures to avoid impacting the important fish migration pathways through the area,” he said. He made the comment after being asked for more details about the company’s work to improve the fish migration pathway through the Hou Sadam.

According to Dr Hawkins, the Hou Sadam pathway is the most recent development and was completed just before Lao New Year in April this year. The approach and methodology the company used in the Hou Sadam fish passage development were the same as those used to improve the pathways in the Xang Pheuak channel in 2012.

The channel modifications were designed by international and local consultants and implemented by MFCB Lao staff with labourers from villages on the Phapheng Sadam and Sahong islands. Dr Hawkins said MFCB policy was to avoid the use of explosives in fish pathway modifications. They used a compressor and jackhammer along with other more traditional methods (fire and water) to break up the bedrock which limits the depth of the smaller upstream entrance to the Sadam channel.

Because it is not obstructed by any waterfalls along its length, the Sadam channel has always been a viable, albeit narrow fish migration pathway across the Great Fault Line of the Lower Mekong River.

The decaying brick obelisks along the banks, once used by French colonial era ships to winch themselves upstream, are evidence that even cargo boats once used this channel.

“We expect the upstream excavation to increase wet season flow and help scour sand accumulations from the downstream end of the channel, thus producing a greater attractant flow for upstream migrating fish,” Dr Hawkins said.