Water quality in watercourses

Water quality in watercourses has improved significantly since the 1970s in terms of nutrient pollution. Micropollutant contamination is the new and biggest challenge at this time.

Bathing water quality

Virtually all rivers and lakes in Switzerland are safe to swim in, in terms of water quality. Thanks to various protective measures and major advances in wastewater treatment in recent decades, the water in Swiss rivers and lakes is now very clean.


A large proportion of the waterbodies in the Swiss Plateau can only fulfil their role as habitats for animals and plants to a limited extent, as a biological assessment of streams and small rivers shows. The species composition in large rivers is also strongly impacted by human activity and invasive alien species. The Red Lists give a clear indication of how the quality of waterbodies is severely compromised; over 50 per cent of all species living in and around them are endangered or already extinct.


Many micropollutants are detected in Swiss watercourses. In small and medium-sized watercourses, pesticides in particular exceed their ecotoxicological limits , whereas in large watercourses this is the case for some medicinal products. In the affected watercourses, sensitive animal and plant species are at excessive risk of harm from these substances. These watercourses are mainly located in the densely populated and intensively farmed regions of Switzerland.

Nutrients in watercourses

Nutrient concentrations in watercourses are highest where many nutrients are discharged via wastewater treatment plants (WWTPs) and from agriculture. This is particularly the case on the Swiss Plateau and on the valley floors. Nutrients enter lakes and the sea via rivers. High concentrations of nitrates in Swiss water contribute to their overfertilisation from nitrogen.

Heavy metals

Heavy metal pollution in Swiss watercourses is on a downward trend.

Last modification 23.08.2022

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