Large-scale infrastructure projects, including dams for hydropower, can severely affect wildlife, ecosystems and ultimately humans.

Unless infrastructure projects are designed to support sustainable development, and in a way that maintains natural capital, in the long term nations will not be able to capitalize on the full potential of these investments.

The challenge of a green economy

With a growing population and increased urbanization, Asian countries are building the water, energy, waste management, and transport infrastructure that will support their needs.

At the same time, “green economy” calls for economic development based on sustainable resource use and management.

But many countries in the Greater Mekong are facing challenges in developing sustainable infrastructure due to institutional, technological, and financial insufficiency. These constraints are particularly acute when it comes to hydropower development.

Energy hungry

An increase in power demand along with inflated forecasts of future demand, volatile prices in international energy markets, and concerns over carbon emissions have intensified interest in hydropower development – one of the Greater Mekong’s major renewable energy sources.

In addition to fueling fast growing economies, hydropower development is promoted by some as an avenue for poverty alleviation or, at a minimum, a way to provide electricity access to the millions of households in the region that are still without electricity.

The long-term cost of dams

Whereas sustainable hydropower could potentially boost economies and help provide energy security, concerns have intensified over the potential cumulative impacts of the proposed dams on the environment, fisheries, and people’s livelihoods.

Agreements have been signed with developers for 12 hydropower projects on the lower sections of the Mekong River. But without proper planning, dam development can seriously harm the environment, and the people dependent on the mighty Mekong.

Damming the Mekong will:
  • impact the region’s natural monsoonal flood/drought cycles
  • block sediment and nutrient transfer, and seriously impact the fish and aquatic life of the river and wetlands
  • require tens of thousands of people to relocate because their homes and land will be flooded
  • impact millions more through changes to habitat, farmlands and wetlands

Impacts of dams on fisheries and livelihoods

Each year, a large and diverse fish migration to spawning grounds takes place along the Lower Mekong River.

Up to 70% of commercial fish are long distance migratory species. If this fish migration is blocked by large infrastructure such as a hydropower development, fish will not be able to reach spawning grounds.

The risk is that fish populations will fall and some species may vanish. The region’s fisheries industry, integral to the livelihoods of 60 million people, may even collapse.
Planned dams on the lower Mekong mainstem could decimate fish populations [CLICK TO ENLARGE]


"WWF supports a 10 year delay in the approval of Lower Mekong River mainstream dams to fully consider the costs and benefits of their construction and operation."

WWF's position on dams in the Greater Mekong

The combined effects of dams already built on tributaries and the loss of floodplains to agriculture is expected to reduce fish catch by 150,000 to 480,000 tonnes between 2000 and 2015.

- ICEM, 2010
In other parts of the world, fish ladders and other engineering techniques have been employed to aid the migration of fish. These kinds of innovations are not suitable for the Lower Mekong River because of the diversity of species and sheer amount of migrating fish.

Likewise, while yield from aquaculture is increasing, this cannot replace the region’s wild fish stocks. There are no realistic alternatives to the river as a source of food security and livelihoods--to replace fish protein with domestic livestock protein would require up to 63% more pasture lands and up to 17% more water, exerting even more strain on forests and water resources.

Tributary dams alone are expected to reduce total fish stocks by 10%–26% by 2030 and dams proposed for the mainstream …could cause a further 60%–70% loss of fish catch.

- Orr et al. 2011

Increased vulnerability to climate change

Maintaining the health of fisheries is not the only compelling reason for keeping the Lower Mekong River free-flowing. As a connected system, unimpeded by large infrastructure, the Mekong River provides natural resilience against the impacts of climate change--particularly in the deltas of the Mekong, Irrawaddy, and other major river deltas.

Studies show that rivers connected to their floodplains tend to be the most resilient whereas river systems that are impeded are more vulnerable to climate change impacts.

The Mekong delta is home to 17 million people and is one of the major rice producing areas of the region, generating up to 90% of Vietnam's rice exports.

If constructed, Lower Mekong River mainstream dams will block the flow of nutrients that feed its unparalled productivity. Furthermore, reduction of sediment trapped by dams would decrease the delta's capacity to replenish itself, therefore making it more vulnerable to sea level rise, saline intrusion and the more severe storms driven by climate change which are exacerbating coastal erosion.