to the new facility, we can clean wastewater a lot more effectively,” says Baumann. The results are impressive: the water treatment facility is one of the main reasons why Lake Brienz is currently in great health, compared with other Swiss lakes. This large lake on the fringe of the Alps, which was still heavily contaminated with nitrogen during the 1980s, is now the cleanest lake in Switzerland. It has a comparatively intact ecosystem, where animal organisms – crustaceans like water fleas, insect larvae and worms – can thrive particularly well. These organisms then serve as food for the fish. If there are many of them in a body of water, this is a sign that the water is relatively unpolluted. One year ago, the positive biological condition of Lake Brienz was documented in a report commissioned by the Federal Office for the Environment. Fish and fishermen endured hard times The lake’s current good condition is in stark contrast with the bleak years of its past. One of the people most concerned about it was Beat Abegglen. He is a trained fisherman and lives in Iseltwald, a small former fishing village on the south bank of Lake Brienz. In the late 1980s, he built up his fishing business there. Shortly thereafter, however, catches collapsed. “In the mid-90s, fish in their fourth year of life weighed between 150 and 200 grammes. At the turn of the millennium, their average weight was 40 grammes,” says Abegglen. “This loss in weight and a drastic reduction in catch sizes are always a sign that something is wrong with the water.” At the same time as Beat Abegglen was making his observations, experts at the water protection office of Canton Berne determined that the water fleas, or daphnia, had disappeared. Water fleas, which form part of plankton, are chiefly eaten by whitefish. These are the most common species of fish in Lake Brienz. Based on all these observations, Canton Berne commissioned a research project aimed at finding out the reasons behind the fall in catches and the disappearance of the water fleas. The investigations showed that the changes observed were connected with the decrease in nutrients in the lake. The main reason for this decrease in nutrients was the massive reduction in the levels of phosphorous – including from faeces and from detergents and cleaning products – entering the lake. This decrease, according to the research report, is in turn due to the “decades of efforts made in technical water pollution control” – in other words, the good work done by the water treatment facility. For Lake Brienz, which already has naturally low nutrient levels, this success in preventing water pollution also had a downside: “The tiny quanThe new Brienz water treatment facility, managed by Michael Baumann, is largely responsible for the good quality of the lake’s water. Beat Abegglen takes a look back on his difficult years as a fisherman. First, catches collapsed. Since then, he has been landing more fish from the lake again. 11
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