Fears of a takeover of the quagga mussel in Lake Zug

Chemical measures, sterilised carp and a task force: the SVP parliamentary group fears a “takeover of the quagga mussel”

The measures taken by the City and WWZ (Zug Water Works) against the invasive quagga mussel in Lake Zug are not enough for the SVP parliamentary group (Swiss People’s party). They are calling for more active action and are putting forward various ideas. What do the Department of Building (Baudepartement) and the Office for Forests and Wildlife (Amt für Wald und Wild) have to say?

At the January meeting of the Zug City Council (GGR: Grosse Gemeinderat), the responses of the City Council (Stadtrat) and the WWZ to the SP (Socialist party) parliamentary group's interpellation on the action against the invasive quagga mussel in Lake Zug were discussed. The parliamentary group submitted the interpellation “Is the city of Zug sufficiently prepared for the quagga mussel?” last August

Among other things, the response explained that lake water was no longer being used for trees and lawns in the city, that more intensive checks were being carried out and that employees were being sensitised to the issue. It is, however, difficult to predict the potential costs in the future. ‘From today's perspective, the WWZ estimates costs in the two to three-digit million range for the entire operating time of the lake water facilities in the canton of Zug,’ the interpellation response states. The SP parliamentary group commented as follows on the answers to its interpellation: ‘The answers seem open-minded and it appears that they are aware of how big the challenges are.’

The quagga mussel is now also causing damage in Lake Zug    Photo: Severin Bigler

The SVP parliamentary group, however, expressed concern. ‘Let's assume the worst-case scenario, with costs in the three-digit million range, which therefore starts at CHF 100 million,’ said Marcus Bühler from the SVP parliamentary group during his speech. If this amount is spread over the lifetime of a lake water power plant of around 50 years, then at least CHF 2 million per year would have to be budgeted just for the cleaning work. The SVP parliamentary group therefore advised proactive action.

Visits to other purification plants
At the Zug City Council meeting, the SVP parliamentary group also raised various questions about the fight against the quagga mussel. ‘Who exactly is in charge of the matter, would a quagga task force be necessary and have chemical measures been tested?’ asked Marcus Bühler. He also enquired whether other purification plants, such as the one in Biel, had been visited by the city or canton for informational purposes. He called on all municipal councillors and city councillors to look into these questions.

In response to an enquiry from the Zuger Zeitung newspaper to the Department of Construction regarding the SVP parliamentary group's thought-provoking ideas, the following statement was made: ‘Lake Zug is a cantonal body of water. The lead for measures to combat/prevent this lies with the canton.’ The city is responsible for implementing the measures when it comes to the water intake points and the utilisation of the lake water for its own purposes. The building department does, however, welcome the idea of a task force under the leadership of the canton.
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‘The City of Zug does not currently utilise any chemical measures, but will closely monitor corresponding developments,’ continued the building department. The plant in Biel is a lake water plant where not only the infrastructure, but also the drinking water treated in the plant must be protected against infestation. The drinking water of the city of Zug is not obtained from lake water.

Sterilised carp are not a solution
On enquiry, Martin Ziegler, Head of the Zug Office for Forests and Wildlife, explained: ‘There is currently an “Invasive aquatic organisms” support group. The last exchange took place at the end of January under the leadership of the Office for Forests and Game. The main focus is on protecting the lakes from the introduction of harmful organisms.’

With the implementation and establishment of protective measures, the focus in future will be on dealing with the quagga mussel in Lake Zug. ‘A coordination body in the form of a quagga task force makes sense for this. Similar to the existing support group, the Office for Forests and Wildlife will take over the initialisation and organisation,’ continued Martin Ziegler.

The lake water plant in Ipsach near Biel has developed a technical solution that prevents quagga mussels from clogging the water pipes at its plant. Martin Ziegler explained as follows: ‘The extent to which such a pioneering system is also suitable for a plant in the canton of Zug must be examined by the respective plant operators, as must possible chemical measures.’

In the GGR debate, the SVP parliamentary group also mentioned that fishermen on Lake Constance use sterilised carp to control quagga mussels. These fish eat the mussels and their larvae. Would such an approach also be conceivable in Zug? ‘The canton of Zug is in dialogue with the aquatic research institute Eawag and specialised environmental offices. They are also working intensively on biological options for combating the quagga mussel,’ replied Martin Ziegler. Only relying on carp against the quagga mussel has not been an option so far.

‘Carp do eat molluscs, but the quagga mussel is only on their menu to a limited extent due to its very hard shell,’ he added. What's more, carp live in the upper water layers. The quagga mussel, however, also lives at depths of more than 100 metres, and reproduces exponentially.