Photo by Tim Mayer
Tim Mayer of Hood River is a hydrologist and jazz musician. As a hydrologist for the U.S. Fish and Wildlife Service, Mayer had the opportunity to assess the environmental, social, and economic impacts of one of these major dam development projects in Southeast Asia.
As of Tuesday, January 9, 2018
In the United States, the era of big dam building ended some 30 years ago. That’s primarily because most of the best dam sites are already utilized and we’ve become much more aware of the environmental problems associated with dams. In the developing world, dam building is just getting started. River systems in Latin America, Africa, China, Southeast Asia, and Eastern Europe are being dammed at a staggering pace.
Tim Mayer of Hood River is a hydrologist and jazz musician. As a hydrologist for the U.S. Fish and Wildlife Service, Mayer had the opportunity to assess the environmental, social, and economic impacts of one of these major dam development projects in Southeast Asia. He wrote, “Our team of biologists and physical scientists from the U.S government evaluated a network of dams being proposed and constructed on the Mekong River system. The work was part of the U.S. International Technical Assistance Program, one face of U.S. foreign aid.”
To see more photos of the Mekong, go to hoodriver news.com/media.
“It was really interesting work and it's a beautiful part of the world. I made this video of images and an original soundtrack to illustrate the project and the issues with the dams,” he wrote.
The Mekong is a river of extraordinary beauty and biodiversity. It originates in the Tibetan Plateau and travels 2,700 miles through six countries before ending its journey at the Mekong Delta of Vietnam and Cambodia. It can be thought of as the Columbia River of Southeast Asia. Until recently, the river flowed freely along its entire course. But that has changed in the last decade. At least six dams have already been constructed on the upper Mekong in China and 11 dams are either planned or being constructed on the lower Mekong in Laos and Cambodia, with dozens more on the tributaries. The dams threaten the people, landscapes, fisheries, and traditional lifestyles of the region.
One big problem with the proposed dams is that they trap sediment and alter seasonal flooding. The Mekong and its tributaries are sediment-heavy rivers, a chocolate-brown color all year. Seasonal floods deposit silt and nutrients on floodplains and in backwaters of the Mekong Delta. These deposits build, nourish, and sustain the rice paddies, wetlands, and fisheries of the region. The Mekong Delta is a low-lying area and it is already threatened by sea-level rise due to global warming. Cut off the supply of sediment that replenishes this area, and you increase the threat of inundation and salt water intrusion from sea level rise. Cut off the supply of nutrients and you force farmers to use costlier chemical fertilizers and you reduce biological productivity in wetlands and backwaters.
The other problem with the proposed dams is the threat they pose to fish and fisheries. The Mekong River is the greatest inland fishery in the world. I’ve heard it said that this single river system produces more fish than the entire continent of Africa. About 60 million people in the region depend on fisheries for their food and livelihood.
As in our country, the challenge with the dams is getting fish around them. There are an estimated 800-1,200 native fish species in the Mekong, including the Mekong Giant catfish, Giant freshwater stingray, and the Irrawaddy dolphin (not really a fish). By comparison, our own Columbia River has just 30 native fish species. With so many different species of fish on the Mekong, the problem of fish passage is very challenging. Each species has unique habitat requirements and differing abilities when it comes to navigating dams. It is uncertain whether many of the migratory fish species will be able to ascend fish ladders or survive the trip downstream through turbines or spillways.
Preliminary studies of the combined impact of reduced sediment and nutrients and the barrier effects of the dams indicate that at least 50 percent of the fishery yield could be lost if all of the proposed dams on mainstem river and its tributaries are built.
Most environmental issues are not black and white, and dams are no exception. On the one hand, these are poor countries and dams are a step toward economic prosperity. It is hard to deny these countries what we already have and take for granted. Dams provide a relatively clean source of energy and reduce damaging floods. For poor countries, the hydropower is an important export.
On the other hand, the people benefiting from the dams won’t necessarily be the people suffering the adverse effects of the dams. Much of the hydropower generated in Laos will be sold to neighboring Thailand. Farmers and fishermen in rural areas whose lives and livelihoods are negatively affected by the dams will likely see few of the benefits.
But the issue shouldn’t necessarily be framed as dams versus no dams. There will be dams on the Mekong and its tributaries. The more appropriate question is: where will dams be located? Our work, and the work of others, has shown that the location and number of the dams on the mainstem and tributaries makes a tremendous difference in terms of impacts. Dams can be located and operated in a way that maximizes energy production but also preserves fisheries, biodiversity, flooding regimes, and sediment transport. Studies suggest that dams on the tributaries of the Mekong may be just as detrimental and just as important to consider as mainstem dams. For example, if all 78 tributary dams are constructed as proposed, one study demonstrates they will produce much less energy and reduce fisheries much more than if the six most upstream dams on the mainstem river are constructed.
The location and deployment of a network of dams to meet multiple objectives is a relatively new approach to hydropower development, one that recognizes all the benefits and impacts of dams as well as the concern for people, wildlife and fisheries, and other natural resources. For an example closer to home, one recent study of the Willamette River hydropower system found that you could remove 12 dams and reconnect half of the river basin while sacrificing less than 2 percent of the hydropower and storage capacity in the system.
Imagine if we had had access to this kind of information when we developed our hydropower system in the Pacific Northwest decades ago. We may have avoided many of the environmental problems we are struggling to address today. It is much easier to avoid a problem altogether rather than trying to fix it later, after it has been created. Developing countries around the world are starting with a clean slate. They have a unique opportunity to develop hydropower in a way that is easy on people and the planet. It’s my hope that we can convince the Mekong countries and other countries around the world to go slow and consider this kind of information when developing hydropower. If we are successful at that, then everyone can win.