Many industrialised countries in Europe and America built dams in the early 20th, or even 19th century. As these infrastructures age, their services may be better replaced by other technologies. Often, this happens when sedimentation builds up in a reservoir, reducing its storage capacity and hydropower potential. What are the options when this happens?
As with dam building more widely, opinion is polarised. A longstanding anti-dam movement in the USA has campaigned for their removal and has had some cases of success. Meanwhile other countries look for retrofitting options. Two contemporary cases illustrate this debate.
This month, two dams were breached in France; the 36-metre high Vezins Dam and another, La Roche Qui Boit, on the same river. Both dams’ usefulness had decreased with age to the extent that neither was particularly economically beneficial. Moreover, they were blocking a river and its sediment flows, leading to the Mont St Michel UNESCO world heritage site, reducing flow to the sea and diversity of river life.
As with many of the dam removal campaigns, the European Rivers Network asserted the importance of restoring the free-flowing river because of its environmental value, especially for migratory fish such as salmon and eels. Indeed, a recent report in Nature argued for the need to conserve such untamed rivers given that only 37 percent remain free flowing globally, whilst 23 percent flow uninterrupted to the ocean. A group entitled “Friends of the Vezins Dam” has asked the regional court to strike down the government’s decision to decommission the dam.
In contrast, in the Blue Mountains UNESCO world heritage site in Australia, debate continues on whether to increase the height of the Warragamba Dam by 14m. It was built in the 1940s and the government wants to increase the reservoir’s storage capacity. However, environmental campaigners and the indigenous communities, who were displaced from the dams’ original construction, are opposing the project. Indeed, UNESCO has issued a warning about the proposal’s potential impact on the ecological integrity of the UNESCO site.
Thus, debates about dams do not end with construction and aren’t confined only to developing countries. This is important to remember given the tendency in many dam projects to overlook the long lifespan of a dam and the processes and costs of eventual decommissioning.
The public and private sector interests in removing dams can divide people as much as when they are built.
Note: This article gives the views of the author/academic featured and does not represent the views of FutureDAMS as a whole.