Vientiane Times, 26 March, 2013
The Xayaboury dam developers have unveiled technical drawings relating to the fish passage tunnels that will be incorporated into the dam, the first on the Mekong mainstream, which is scheduled for completion in 2019.
Fish will be able to swim freely up or downstream through the Xayaboury dam, they say, as a sophisticated series of tunnels and passages has been incorporated into the design.
A group of Vietnamese reporters visited the construction site last week, and one of the things they were keenly interested in was the fish passage arrangements, along with the sediment flushing facilities.
Lead Engineer of the Xayaboury Hydro Electric Power Project, Mr Prat Nantasen, explained the basic principles of the tunnels using a diagram.
The red arrows represent the downstream migration tunnels, while the black arrows represent the upstream ones. It is anticipated that all fish species will be able to pass through the tunnels, each of which is three metres wide and six metres high.
The upstream tunnel will wind its way gradually up to the height of the dam wall, to ensure that the current is not too strong for the fish to pass, while the downstream tunnel will divert fish to the side of the dam in order to avoid the turbines.
The project hired fish specialists AF Colenco and Teraplant to study fish migration in the river and produce the best system to allow fish to pass up and downstream of the dam.
The Vietnamese reporters were happy with the information they received on both fish passage and sediment flows.
Mr Prat said they had recently observed a large fish in their camera trap near the dam. The fish was over two metres long, but they did not know what species it was.
Since specialists have been surveying fish populations in the area, they haven’t seen any giant catfish near the dam. Local fishermen say they haven’t caught one for many years.
The project developers plan to breed giant catfish in the Mekong near the dam. This is currently being done successfully on a commercial basis in Thailand, and the developers are seeking advice from those involved in the scheme.
The Vietnamese reporters visited the dam construction site before touring the newly built resettlement community at Na Tor Yai village just outside the provincial capital.
The dam is scheduled for completion in 2019, with the bulk of the electricity to be sold to Thailand. The project is 10 percent complete following the groundbreaking ceremony held in November last year.