First, the big dam floods a lot of land. It isn't just any land that gets flooded, it is the most fertile growing land available: the floodplain. The richest farms and forests are destroyed by filling a big dam, leaving the rocky slopes. Next there are the social costs, such as the displacement of the farmers who traditionally work the fertile valley floor. The article sites the loss of fisheries and tourism as downsides, but frankly, where I have seen big dams the fishing and tourism have increased. Motorized recreation on lakes is more popular and more of a money maker than human-powered river recreation, but it is unsustainable and contributes to the pollution of the water. Water quality may also be compromised by the land it floods, depending on what has been done there. Fishing in reservoirs is easy, but dependent on stocking, and the native and migrating fishes of the river are killed or displaced.
Around the world there is currently a resurgence in dam building, because every reasonable government is concerned about the ramifications of peak oil. The giant Three Rivers dam in China has been a disaster and much has been written about it. The last of the magnificent free-flowing rivers, like the Amazon, the Mekong, and the Congo, are slated to be harnessed. As with all giant construction, these projects are driven by multinational corporations with no concern for the stability and sustainability of local communities. They are not looking out for the people, or the rivers. They are concerned only with the bottom line, and they still have a lot of momentum after 50 years of amazing profits. So it is up to us to keep them from destroying our planet for future generations.
I am a river runner from Tennessee, and when I was a child there was a great battle between conservationists and the TVA about a tiny fish named the snail darter. At that time I thought all dams were bad. Later I was there to see the beginnings of the damming of the Rio Bio Bio in Chile in 1992. I was active in the American Whitewater Affiliation, whose mission is to conserve and restore America's whitewater resources while also increasing opportunities for whitewater recreation. I was attuned to the FERC relicensing process for dams, and working one license renewal at a time to get dam management plans to include riverbed flows as part of the contract.
Gradually I realized that opposing all dams and making my decisions purely based on recreational values was short sighted. We do face an energy crisis. We are going to be hurting for power. So my position has changed.
1) I am in favor of the use of small, local hydropower structures. I would like those who favor decomissioning these small dams for fisheries and recreation purposes to please balance their views with the knowledge that communities that have local clean energy sources will be the place to live in 100 years. Rather than removing the small dams that exist, we should be modernizing them with fish ladders and the best of power generation equipment. New local hydropower projects should be considered by communities with that resource, and constructed using the very best of technology and science supporting them.
2) Modern large dams already in existence should not be removed until they have been used up. A giant dam like Hoover Dam on the Colorado river can only operate so many years before its reservoir is filled and the water level behind it rises. If we were to do nothing about this, the dam would become a very tall waterfall which would then be removed rather quickly by erosion. We need to consider what we can do about large dams, or entire dam systems, that become ineffective because of sediment load. I can imagine someone proposing that we truck away the sediment and keep operating the dam, but I am pretty certain that at that point the energy expended to keep the dam running may become more costly than the benefits of its operation. We need to get real about where that point is, and consider how we will deal with mega-dams that are no longer useful and potentially quite dangerous.
3) Large new dams should be stopped. It is too late to stop the Three Rivers Dam in China, unless an earthquake or flood takes it out. But maybe we can stop the damming of the Amazon and a few other precious free-flowing gems. Toward this purpose, I will begin to post more regularly about the battles that we face, and to do my usual letter writing directed at the governing bodies of nations facing these questions.
4) Small dams on tributaries of the giant rivers should be considered, especially in communities where there are no other reasonably available energy resources. The beauty of small local dams is that the people who pay the price in land and fisheries are the people who gain the benefit of the electricity. Another major plus is that no grid is required. No transfer stations or high power lines must cross the countryside. The expense of energy delivery is substantially reduced when the energy is local.