1.Please provide a list and very short summary of the project(s) you have worked on and their status.
I work on the removal of the Krebsbach dam in Germany (in 2007), the second removed dam in Germany. It was an 18m high earthen dam built for industrial water supply in 1962. In 1989 the purpose ceased to exist. Then in the 90s the security and structural obsolescence problems emerged. In order to meet the new flood criteria a comprehensive expensive rehabilitation was necessary. So the owner, a regional public water supply agency in the province of Thueringen, decided to remove it. The unique aspect of this dam removal is that the owner has formed superficially the former impoundment. It has developed a meandering channel for the small river in the impoundment area which was 700 m long. The channel was stabilized by stones and 10 chutes in the channel because of the relatively high slope. The official reason for human intervention was the expectation of a bigger threat of flooding to three small villages downstream after the removal. Higher retention was aimed for in order to hold back water in cases of a flood. The sedimentation was relatively low, on average 35 cm in the impoundment area (up to 2.5 m close to the dam structure). For the expected transport of some sediment a sedimentation pool was created directly downstream after the former dam structure. Totally 1.2 million Euro was spent for this removal, which is high.
One year after the removal the development of the impoundment area is as was expected. This means the channel stability still exists, there are small amounts of erosion and the biodiversity is increasing, although not like in the case of natural impoundment development. Only the return of the brown trout did not happen, due to some phosphates and other contaminants, which came from a small town upstream of the dam.
If we analyze this kind of artificial channel forming after a dam removal, we can state the following aspects: Although the artificial channel forming in that case happened the first time, this should be included in the discussions on what to do with an impoundment area after removal if the case is in a region with high population density and if downstream people live directly near the river. People who live downstream of dams which are planned for removal will have concerns because of floods. But this artificial channel forming needs more time and particularly more money compared with natural development of impoundment areas.
This artificial channel forming of the impoundment area can be included in the considerations in densely populated regions like Central and Western Europe, but not in the USA, Canada or Australia.
2.When approaching a dam removal project, what is the first thing you have to know, the first step, the first thing one should tackle?
Every dam removal project will have ultimately positive ecological impacts. Maybe in the short-term or even medium-term there can be some important negative impacts (for example contaminated sediments or covering of spawning habitat), but in long-term the positive impacts will dominate.
Before deciding about a dam removal project, the expected ecological, geomorphological, social and economic impacts should be assessed as well. It is important to take measurements in order to mitigate potential negative impacts and to improve the positive impacts.
Also it is important to include all stakeholders in the dam removal decision and implementation process. This ensures that the dam removal project will be highly successful. Otherwise there may be some protests by people living around and downstream of the dam and reservoir. For example affected people can have concerns about flood danger downstream of the dam or about decreasing of the value of the their houses and land around the dam reservoir. Also the environmental organization can give some very important proposal how to implement the project concerning some threatened species. This is important if the owner or project implementer does not have enough financial capacity to do sufficient assessments before project implementation.
If a dam still has important benefits it will be very difficult to reach the removal of that dam, even if it would bring many ecological benefits like opening of hundred of kilometers of spawning habitat for salmon. In those cases, a very strong campaign is necessary in order to convince the public and political representatives who control agencies like FERC, which re-licences projects. If there is a dam that no longer provides benefits and the rehabilitation is expensive, the probability of removal can be very high.
Start a campaign for dam removal if there is a dam which has limited or no benefits and security and ecological concerns and has to be relicensed. This offers a higher possibility for success.
3.Considering all the cases you’ve encountered, what makes the strongest argument for removal?
The main reason for dam removal is economic. Other than that, security and ecology are also important. The security aspect is closely connected to the economic one. If there is still an important benefit from the dam, the dam will be rehabilitated in most cases. The ecological argument is often decisive if it is economically expensive to rehabilitate the dam or the legacy/policy demands removal. In these cases, there is often a public demand for removal.
4.Who are your river restoration heroes, and why?
If there are heroes, they are the NGOs that campaign for the removal of dams or make the public aware of that issue.
5.Do you anticipate any repercussions for river restoration efforts from the financial crisis?
I guess the financial crises may affect dam removal efforts negatively because in such situations governments will decrease the budgets for ecological and social projects. But in some cases the financial crises may be positively if the operator has a reduced budget for rehabilitation of dams.