Dams and the Politicization of Science

For almost two years, the sensational water conflict brewing in Southeast Asia was a hot topic, drawing the attention of global leaders and major newspapers. Laos was planning to build the enormous Xayaburi Dam across the Mekong River, angering downstream countries that depend on the river for food security. Prominent global politicians, including Hillary Clinton, urged Laos to act in an environmentally responsible manner. Regional leaders, especially from Vietnam and Cambodia, called for a delay in the project. I was working for International Rivers at the time, and we were constantly responding to requests from journalists who wanted to gauge how far the conflict would go.

In December 2012, Laos suddenly announced that it had re-designed Xayaburi Dam to be environmentally safe and that it would proceed with construction. The government spokesman downplayed the project’s potential impacts on Mekong fisheries, claiming that a new “state-of-the-art” fish passage would allow migrating fish to travel safely past the dam. Laos promised to share its new fish passage design with governments and the Mekong River Commission. Many felt that the concerns with the dam had been resolved. Media attention began to fade away. The international community stopped monitoring the project, and Laos was able to proceed without scrutiny.

Now, Xayaburi Dam construction is 40% completed, and the potential for conflict remains unabated. Laos’ central promise to neighboring countries – to design a safe fish passage – remains unfulfilled. To date, neither the regional governments nor the Mekong River Commission have been given the opportunity to review the design of the new fish passage. The continued secrecy suggests that Xayaburi’s developers might not be able to deliver on their promise after all.

It is essential that the fish passage works. With 781 known fish species, the Mekong is the world’s second most biodiverse river. With 2.1 million tonnes of fish yielded each year, the Lower Mekong is also home to the world’s largest inland fishery, and migratory fish comprise at least 39% of that yield. The four countries of the Lower Mekong Basin have the four highest rates of fish consumption in the world. In Cambodia, for example, people consume 40.3 kg of river fish per person per year, making fish the second most consumed food item after rice. At least 229 fish species have been recorded near the Xayaburi Dam site, including 70 long-distance migratory species.

Earth Rights International

The Lao government is working with Thai company Ch. Karnchang to develop the Xayaburi Dam. They are relying on European and US engineering companies to design the fish passage facility. The Pöyry Group (Finnish, Swiss) is leading the effort, along with Terraplant and AF Consult (Swiss), KGAL (British), Xylem Inc. (US), and Andritz (Austria). Together, these companies have taken an unconventional approach that contradicts the basic principles of fish passage science. There is a lot that could go wrong.

For years, the Xayaburi developers have claimed that their new fish passage facility will allow fish to swim safely past the dam. This is a challenge, because there are so many different types of fish – each with different sizes and behaviors – that would need to pass the dam. According to early reports, the Xayaburi developers will provide several options for fish to pass the dam: an 800-2,000 meter long ladder, a fish lift and a navigation lock operated to facilitate fish passage upstream; a bypass fish collector; and “fish friendly” turbines for downstream migrations. All of these components have been used in some shape or form in other fish passages around the world. However, the Xayaburi developers are attempting to build this fish passage facility at a scale and complexity that are unprecedented. Here are the main challenges.

Step 1: Selecting target species to be conserved

In fish passage design, the first step consists of selecting target species so that the facility can be designed to accommodate the specific behavior or constraints inherent to these species. Thus, the size, location, and design of the facility depend on whether the target species are large or small, are strong swimmers or not, progress in the middle of the river or along banks, etc. The Xayaburi Dam developer has indicated that it will attempt a one-size-fits-all approach to fish passages, rather than tailor the design to specific species. However, no fish passage in the world has ever used a generic design to accommodate such a wide variety of fish species at once – in this case, ranging from the 3-meter-long critically endangered giant catfish to the 12-centimeter-long very abundant Siamese mud carp, also essential to food security.

Selecting target species for the passage’s design implies ignoring other migratory species. The choice is not difficult in temperate rivers where the number of migratory species is very limited (mainly salmons, eels, and shads), but is a heavy responsibility in tropical countries characterized by a very high biodiversity. In the case of Xayaburi, the choice must be among 70 migratory species. So on what basis is the selection made (biodiversity conservation, food security), and by whom (who selects, how consultative is the process)? What will become of the other migratory species for which the fish passage is not specifically designed? There is no indication that the developer has tackled these questions. External stakeholders have not been consulted.

Step 2: Attracting target species to the fish passage

Once target species are identified, it is essential that the water currents through the fish passage mimic the water currents that would attract these species in natural conditions. At Xayaburi, migratory fish are scattered across an 800m-wide river, while the fish pass entrance will be 10m wide at best. Fish have no reason to find and enter the ladder or lift, unless they are attracted by a specific discharge or water current that mimicks the streams and habitats they ultimately seek. Without proper attraction flows, migratory fish simply will not find the fish passage entrance. At Xayaburi, there is no indication that the developer has identified research on attraction flows as a priority.

Step 3: Ensuring that target species have the ability to swim the passage

Once the target species and the attraction flows are identified, fish passage science requires an understanding of the swimming capabilities of each species. In particular, what maximum flow velocity can target species swim against, and how long can they keep swimming against such current? If the water flow in a fish ladder is too strong, fish will not be strong enough to swim up the pass. Swimming ability depends on the species and its size, hence the importance of clearly identifying the target species. 

Designing an effective fish pass also requires knowledge of the maximum height a fish can jump. In the Xayaburi developers’ initial fish passage design, the height of each of the 106 steps of the fish ladder was almost three times the size of the dominant fish species. The developers later recognized that the length of the fish pass would have to be significantly extended to reduce the slope and height of the steps, but this acknowledgement itself reflects how uninformed and inadequate the dam’s fish passage design has been.

Fish cannot swim several hours without interruption, which implies that they must rest in some places during their daily journey (if not, they would drift back). In temperate countries, long fish passage facilities include cross-walls behind which fish can rest, or resting pools. At Xayaburi, the developer has not indicated how resting areas will fit into the design.

Build now, adapt later?

The Xayaburi developers began construction before finishing the fish passage design. It is likely that this decision was motivated at least in part by the dam’s investors. A review of the Xayaburi Dam’s power purchase agreement by International Rivers, for example, revealed that the developers were required to pay up to $210,000 per each day that construction was delayed. This created strong incentives to proceed without a proven fish passage facility in place.

Yet it was a risky decision to proceed without confirmation that the fish passage facility will work. In a November 2011 review of the project, the Mekong River Commission Secretariat concluded that “conducting specific investigations before (rather than in parallel with) dam construction will reduce risks, including those of transboundary and cumulative impacts, and avoid ‘regret measures’, actions that may ultimately be inappropriate and lead to expensive and/or irreversible unintended negative impacts.” The Secretariat recommended taking two years to collect more information for the fish passage before beginning construction, but this recommendation was not taken. Even basic data collection did not begin until construction was already underway. Two years later, it appears that key data is still missing. In the absence of this crucial data, the fish passage design is based largely on guesswork.

Missed opportunities for collaboration

Despite the risks, the Xayaburi fish passage design is proceeding behind closed doors, and current dam designs have not been shared with other regional governments, as promised two years ago. No independent monitoring is allowed at the dam site, and there has been no collaboration or information sharing with regional scientists. As a result, the dam developers have not benefited from the expertise, data, and constructive criticism of regional and international experts.

A failed Xayaburi Dam fish passage design will bring high costs. These costs will be borne by citizens living along the Mekong River, not by the Lao government officials and Thai businessmen who have already profited from the construction of the dam. A lack of monitoring by the international community compounds a dangerous situation in which the Xayaburi developers have no incentives to act responsibly.

Laos is now using similar strategies to push forward a second dam, Don Sahong, on the Mekong near the Cambodian border. At least nine others are planned. If these projects move forward, it will be crucial that the region’s governments create space for real dialogue based on scientific evidence. This means transparency in the details of dam designs, adequate time set aside for debate before construction begins, and outreach to independent experts who are not on the payroll of the developer. Without these processes in place, decisions on whether to dam the Mekong will continue to be based on power and corruption, which is a recipe for conflict.