Small lakes in the Canton of Bern are facing increasing pressure from pollutants, including pesticides, algae, and so-called “forever chemicals.” While the Oeschinensee remains largely healthy, the Lobsigensee is under strain from agricultural runoff, and the Grosser Moossee is showing signs of contamination from potentially historical sources. The situation highlights a growing concern for the ecological health of these vital freshwater ecosystems.
Scientists have recently detected per- and polyfluoroalkyl substances (PFAS), often referred to as “forever chemicals” due to their persistence in the environment, in the Grosser Moossee near Moosseedorf. The origin of these substances remains unclear, prompting further investigation into potential sources, including historical landfill sites. This discovery adds to the existing challenges faced by Bernese lakes, which are increasingly vulnerable to agricultural and industrial pollutants.
The Lobsigensee, located in the Seeland region, is particularly affected by agricultural pressures. Runoff from nearby farmland introduces pesticides and other chemicals into the lake, impacting water quality and potentially harming aquatic life. The lake’s shallow depth and limited water exchange exacerbate the problem, making it more susceptible to pollution. According to data from 2023, the Lobsigensee has a surface area of 1.73 hectares and a maximum depth of only 2.5 meters , making it particularly vulnerable.
The Grosser Moossee, another lake in the Canton of Bern, is now the focus of investigation following the discovery of PFAS. These chemicals, used in a wide range of industrial and consumer products, do not break down easily and can accumulate in the environment and in living organisms. The presence of PFAS in the Moossee raises concerns about potential health risks and the long-term ecological consequences. The exact source of the contamination is currently unknown, but authorities are exploring the possibility of a connection to a former landfill site.
Fortunately, not all lakes in the region are facing the same level of threat. The Oeschinensee, situated above Kandersteg in the Bernese Oberland, is currently considered to be in relatively great health. With a surface area of 1.1147 km² and an average depth of 56 meters , the Oeschinensee benefits from its high altitude, glacial origins, and relatively pristine surroundings. However, officials caution that even this seemingly healthy lake remains vulnerable to future pollution.
The situation underscores the need for increased monitoring and stricter regulations to protect Bern’s small lakes. Agricultural practices, waste management, and industrial discharges all contribute to the problem, requiring a comprehensive approach to mitigation. Local authorities are working with farmers and other stakeholders to implement best management practices and reduce pollution at the source.
The UNESCO-recognized Lobsigensee, a site of prehistoric pile dwellings, is particularly sensitive. The archaeological significance of the site adds another layer of urgency to the need for preservation.
Looking ahead, continued research and monitoring are crucial to understanding the extent of pollution in Bernese lakes and developing effective solutions. The Canton of Bern is expected to announce further measures in the coming months to address the issue and safeguard these valuable ecosystems. The long-term health of these lakes depends on a collaborative effort between government, industry, and the public.
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