Many dams are under construction, in the pipeline or proposed for rivers in Cambodia, Vietnam and Laos that will have a dramatic impact on Cambodia. While a case can be made for the relatively cheap, carbon-negative power they produce, they are ultimately a mixed bag when all factors are considered. In fact, large numbers of dams are slated for removal in America over the impact they had on wildlife, supported by the Endangered Species Act.
For example, several dams will be removed from the Klamath River that passes through southern Oregon and northern California on its way to the Pacific Ocean. Four dams were built about half a century ago that have blocked the passage of salmon to their former spawning grounds. Salmon are anadromous fish that spend most of their three-year lifespan in the ocean but start and end their lives in small rivers and streams, sometimes hundreds of miles from the ocean.
In one of the most fascinating and mysterious phenomenons of the natural world, after roaming vast stretches of ocean for three years, they return to spawn on or very close to the exact spot where they were hatched. They grow as large as 40 kilograms and are one of the tastiest fish one can eat. A healthy salmon run is capable of feeding large numbers of people and thus should not be easily discounted.
The dam builders knew their work would sharply reduce salmon runs but considered progress, in the form of cheap electricity, more important.
As the dams on the Klamath came up for licence renewal, the Endangered Species Act kicked in and the owners were told they needed to adapt them for fish passage if they wanted to continue to use them. When the numbers were crunched, however, the cost was too high and economics dictated that the preferred action was removal.
Cambodia is about to trade its abundance of fish, the primary source of protein for 80 percent of its population, for electricity. Cambodia's 25 percent per year increase in demand for electricity can mostly be attributed to powering the new air-conditioned economy. So that's the trade off: millions of fish for urban air-con.
Worse yet, the Mekong River Commission, which ostensibly would have a role in protecting the river's environment, is too weak to demand ecological considerations. It is possible to build small dams that would minimise disruption of fisheries, but these are not the type of dams being built.
Dams on the Mekong mainstream and its tributaries may lead to the reduction, even possibly the end, of flooding on the Tonle Sap lake with catastrophic consequences for the many Cambodians whose lives depend on fish that feed on the nutrients brought by flooding.
An additional factor that is not being adequately considered is the shortfall of water during the hot season when the electricity is most needed. As I understand it, under current plans, some dammed rivers will dry up completely during the hot season, obviously not the best conditions for fish or any wildlife that depend on the river.
Other negative effects include the loss of fertile riverside land and displacement of people, but the loss of fisheries is the most serious consequence of the dam building.
The push for dam construction is so strong that I have little confidence environmental damage assessments will make an iota of difference to the authorities. It is too bad Cambodia could not learn from others' mistakes.