VO XPC evaluates whether Mekong fish would be able to use a fish pass at the run-of-river Xayaboury hydropower dam INTRO: Xayaboury Power Co Ltd is currently studying fish swimming ability to evaluate the effectiveness of a demonstration fish passage facility at the Xayaboury hydropower project in northern Laos. According to Xayaboury Power Company Deputy Managing Director, Rewat Suwanakitti, the Xayaboury dam will be equipped with a number of fish passage facilities, not just one as in other dams, so it is confident that fish will be able to swim up and down the river after the dam is built. STORY: Deputy Minister of Energy and Mines, Viraphonh Viravong visited the site on Monday the 9th of June, accompanied by officials and members of the media. In response to concerns raised by Mekong Commission Committee stakeholders and experts, the initial design of the Xayaboury scheme was modified to incorporate sustainable solutions for local Mekong fish populations to pass through the hydropower dam. An experimental facility with a 24 metres long flume has been built at the construction site to investigate the specific swimming abilities of different species of fish. Three different experimental techniques are being applied to 'lead' species including Pa Pak Ta Leuang (Hypsibarbus Pierrei), Pa Tep (Paralaubuca Typus), Pa Dok Ngieu (Cycloheilichthys Repasson), Pa Nyon Nuat (Clupisoma Sinense), Pa Soi Hua Po (Henicorhynchus Siamensis) and Pa Nyon Thong Kom (Pseudolais Pleurotaenia). Interview: Guillaume Morier-Genoud, Project Engineer Hydraulic Poyry According to Xayaboury Power Co Ltd, Engineering consultancy firm Poyry Energy was hired to work on the project. Poyry Energy then contracted Fishtek Consulting to evaluate whether Mekong fish would be able to use a fish pass at the run-of-river Xayaboury hydropower dam. The tests being performed include the velocity barrier test, the burst swimming test and the 'umax' method. Tests will be completed in the next few weeks and conclusions about the design will then be made. Fishtek is a specialised international fishery consultancy based in Devon, UK. They are a leading British consultancy in evaluating the interaction between hydropower projects and fish. Interview: Tobias Coe, Director Fishtek Consulting' technical Fishtek Consulting' technical director, Tobias Coe said the fish pass design was based on the best practice principles of taking the swimming abilities of fish into consideration when designing fish pass systems, tailoring them to specific species. Interview: Tobias Coe, Director Fishtek Consulting' technical Fishtek Consulting' technical director, Tobias Coe said "what that means is we are not taking generic principles of fish pass design. This fish pass will be designed for the species that are present in the river Mekong." He said, different tests were underway in the stream looking into the behaviour of the key fish species at different water velocities and how they react to obstructions, as well as the pure physiology of the fish and their swimming capabilities. Interim conclusions confirm that a design velocity of about 1.2 metres per second can be used in the main slots of the fish pass. At this speed most of the fish species require several attempts to enter the flume during the velocity barrier tests. Construction of the US$3.5-billion 1,285 MW Xayaboury hydropower plant began at the end of 2012 and is now 30 percent complete. Interview: Rewat Suwanakitti,DMG, Xayaboury Power Company According to Xayaboury Power Company Deputy Managing Director, Rewat Suwanakitti, These passages are designed with a natural setting in order to facilitate fish passing of all sizes and species across the width of the river in both upstream and downstream directions. Rewat said, One approach is a land-based "fish ladder" that goes around the barrage at an appropriate gradient or slope. Interview: Viraphonh Viravong, DM of Energy and Mines The DM said, Fish swimming ability tests began in May this year and are ongoing. They will allow scientists to understand the behaviour of fish species and allow for the optimum design of the structures to allow all key fish species to pass through the hydropower dam. The current fish pass design proposes four vertical slots of different sizes controlling the water flow between pools 20 metres wide and 8 metres long. Fish have to burst-swim through the slots before traveling the pool upstream to the next set of slots. The dam is set for completion in 2019. Once the dam is operational, it will generate a large amount of revenue for the Lao government, which will be used to reduce poverty. The government expects to generate nearly US$4 billion in the form of royalties, dividends and taxes throughout the 29 year concession period. Commercial operation is slated to begin in 2019. The dam's operational phase covers 29 years of the concession agreement from 2019 to 2048, before ownership is transferred to the Lao government.

• published: 21 Jun 2014
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