The lake should be empty in time before the frost comes. Almost two million cubic meters of water should disappear in the next six weeks – from a body of water the size of about 42 football fields. The water has to go because the lake has to be repaired, it will flow away via the adjacent stream and a couple of rivers towards the Main.
It is a huge renovation project that has now started in Lower Franconia: Lake Ellertshausen, the largest reservoir in Lower Franconia and a popular excursion destination in Lower Franconia, which is otherwise not very rich in lakes, is getting new underground pipes and technical devices. The main line is ailing, eaten away by bacteria. “The whole lake is on the line,” the water masses “press” on it, says the head of the water management office in Bad Kissingen, Leonhard Rosentritt. If one does not act, it would burst for the foreseeable future. The consequences would be devastating: “This would cause a major flood in the area,” says Rosentritt. A tidal wave, as feared at the Steinbachtalsperre during the floods in North Rhine-Westphalia, would be possible.
So in Lower Franconia you take around five million euros, dry, de-sludge, renovate. The draining of water, says Rosentritt, is actually the least of the problem. To do this, he only “opened a gate valve” on Wednesday, he says. Since then, a controlled amount of water has been draining off until the level has dropped by one meter. That is common anyway, says Rosentritt. The artificial lake serves as a rain catchment basin and is lowered annually so that it does not overflow and continues to protect against flooding. In the next step, a ramshackle dam between a fore lake and the actual lake will be secured and, finally, more water will be diverted. Several construction companies are then involved in the main work, the renovation, says Rosentritt.
The Ellertshäuser See is almost 65 years old, in 1957 it was put into operation near the Markt Stadtlauringen, and since then it has also served as a water source for the dry Lower Franconia. The lake became a bathing resort, there are holiday homes, a lakeside restaurant, surfers, but now people have to do without it – and go much further to swim – to Middle Franconia, for example, to the also artificial Franconian Lake District.
In 1983 the lake was drained once. A major encroachment on nature, then as now. But the water protection expert Rosentritt does not see any errors in the original construction planning. It is normal for pipes to wear out and have to be replaced, 1983 – and now again. For the next time, however, they are now building a new, second dam as a precaution, which allows repairs while part of the water remains in the lake. Why not in 1983? At that time, the corresponding pipes were not yet due for the renovation, it was not necessary to replace them, says Rosentritt. But the bacterial infestation was probably not “on the screen”.
The largest reservoir in Lower Franconia is almost 65 years old, and in 1985 the water had to give way for the first time.
(Photo: Nicolas Armer / dpa)
How the water is now giving way can be followed week after week with the measuring tape, says the local mayor in an information video. Efforts are made for transparency, emphasizing that nature conservationists are also involved. Once the water level has dropped to about ten (from a total of 15 meters water depth), the fish and mussels are taken out of the lake. One reckons with ten to 20 tons of fish, says Rosentritt, a specialist fisherman fishes them out. Larger fish are then sold to the catering industry, for example, while smaller fish are relocated to a fore lake that remains full.
From November the sludge will be removed, examined and distributed over fields or used for noise barriers. From spring to summer 2022, a thorough renovation will take place in the tunnel below the lake and around the last 100 meters of the pipeline, which can only be reached when there is no water in the way.
After completion of the work, the fish from the fore sea should return to their old habitat and bathing could then be done again in 2024. “That,” says Rosentritt, “also depends on God, depending on how much he lets it rain and how quickly the lake fills up”. If the trend of the rather dry past years continues, it could take longer.