Environment Harmful quagga mussel found in Lake Zurich

Harmful quagga mussels have been discovered in Lake Zurich. In order to prevent the invasive mussels from spreading to other lakes, boats are no longer allowed to enter the water in Lakes Greifensee, Pfäffikersee and Türlersee with immediate effect, as announced by the Department of Public Works on Friday.

Boats that are already in one of these lakes may remain there, according to the press release. From 2025, captains who have a dry berth will also be able to launch their boat in Lake Greifen, Lake Pfäffikon or Lake Türler again, as the Department of Civil Engineering explains in its press release.

However, a "home waters" rule will then be introduced for boats registered in the canton of Zurich: Moving from one body of water to another will be prohibited. Boats from outside the canton will no longer be allowed to enter Zurich's lakes and river sections from 2025.

These transitional measures will apply until the introduction of mandatory ship registration and ship cleaning for registered boats that move from one body of water to another. The canton is currently working on the corresponding legal and organizational basis.

These measures are intended to prevent the quagga mussel from spreading to Lakes Greifensee, Pfäffikon and Türler and endangering their valuable and protected ecosystems.

Quagga mussel in Lake Zurich for some time now

A team of researchers from the aquatic research institute Eawag found individual specimens of the quagga mussel in the Zurich lake basin and off Thalwil at the beginning of September, according to the Department of Civil Engineering. "Based on the size of the mussels, it can be assumed that they have been in Lake Zurich for some time."

This mussel originally comes from the Black Sea region. However, it is now widespread in large parts of Europe and North America. It is particularly common in lakes and slow-flowing rivers.

It is also spreading in Swiss lakes and causing problems, according to the Zurich Building Department: "It displaces native animal species and can block water intakes for drinking water and energy use as well as overgrow shoreline and port facilities."

Once the quagga mussel has been detected in a body of water, it is almost impossible to get rid of it. It is therefore crucial to protect those bodies of water in which it does not occur according to current knowledge.