MIREILLE GUGGENBÜHLER Water plant manager Michael Baumann stands on the roof of the new facility in Brienz, Canton Berne, and allows his gaze to wander. Below are construction vehicles, behind him the clarification tanks and in front of him, three hundred metres away, are Lake Brienz and Hasli beach. Residents of the Hasli valley come here every summer to swim. Today, there is no-one to be found. Small waves break on the shingle beach; the emerald-green water is otherwise calm – high season has long since ended, and the ships are no longer running. Around a hundred metres from the lake shore, 18 metres deep, purified water from the treatment facility flows into the lake. “The quantity of wastewater that we process here is highest during peak season in the summer,” says Baumann. This is when the neighbouring campsite is occupied, the Ballenberg open-air museum is open and the hotels are fully booked. In winter, on the other hand, it takes longer to clean the waste water. “The microorganisms that purify the water move more slowly in the winter cold – just like people,” explains Baumann. Worms, insects and crabs thriving like never before The water treatment facility at the upper end of Lake Brienz is new, and replaces the previous facility, which dates back 50 years. The new facility is computer-controlled and is monitored by Michael Baumann and his colleagues. Its construction is not quite complete, but it is already operational. The previous facility was also able to break down numerous chemical compounds. However: “Thanks All of a sudden, Lake Brienz was too clean for some The largest mountain lake in Switzerland has seen some ups and downs. Back in 1980, it was “over fertilised” – too high in phosphates. Then, in the space of a few years, it became so clean and free of nutrients that the fish died of hunger. Since then, the lake’s ecosystem has stabilised, and the fish are doing better. Lake Brienz, flanked by the slopes of the Bernese Alps, is probably the cleanest lake in Switzerland today. For a long time, this was not the case. Photos: Danielle Liniger Higher, farther, faster, more beautiful? In search of somewhat unconventional Swiss records This edition: On the shores of the cleanest lake in Switzerland. 10 Report
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