It’s a pseudo-solution

The phosphorus content in Lake Zug is too high, and David Meyer has launched a cantonal initiative that proposes a technical cleaning of the deep water of the lake.
 

He is thereby opposing the aeration project that has been pursued so far, and is even leaving his party for the initiative. But the canton considers the idea neither proven nor practical.

At the meeting of the Zug Cantonal Council (GGR: Grossen Gemeinderat) in mid-June, David Meyer, the leader of the Zug Green Liberal Party (GLP) parliamentary group, surprisingly announced his resignation from the party. At the same time, he launched the cantonal “Zuger-See-Initiative” (Lake Zug Initiative) as an independent. The initiative calls for a technical cleaning system for the deep water of the lake. “The phosphorus pollution of Lake Zug has been an issue since my youth. But hardly any progress has been made since then,” he says. “I no longer want to just stand by and do nothing.”

It is well known that the phosphorus content in Lake Zug is too high; it has, in fact, the highest phosphorus pollution of all major Swiss lakes. But there is already another proposal to counteract this: lake aeration. The Canton of Zug spearheaded this project and collaborated with Eawag, the aquatic research institute of ETH Zurich. While the Canton of Lucerne pledged its financial contribution to the project, the Schwyz Cantonal Council (Kantonsrat) rejected the joint aeration project in April 2025, as reported by the Zuger Zeitung newspaper at the time, and the project has been on hold since then. The federal government (Bund) has the overall responsibility for water protection, but its decision is still pending.

David Meyer wants to clean the deep water
According to David Meyer, lake aeration would not solve the problem, but merely shift it. It would simply mix the "polluted deep water" with the surface water and discharge it into the Lorze River, and ultimately into the drinking water supply. "It's a sham solution," he says.

He therefore proposes a technical purification plant that would remove not only phosphorus, but also PFAS and micropollutants from the deep water. "It's quite simple," he says. The water would be piped up from the depths and pumped into a treatment basin. There, it would be purified using powdered activated carbon and precipitants, and would then returned to the lake. "The exact composition of the active ingredients in the treatment basin would still need to be optimised, but the basic principle is proven to be effective," says David Meyer. He estimates the project costs at CHF 15 to 30 million, with annual operating costs of around one million Swiss francs.

Lake Zug has the highest phosphorus levels of all major Swiss lakes. Various solutions are now being considered    Photo: Jakob Ineichen
David Meyer has launched the "Lake Zug Initiative" and has announced his resignation from the Green Liberal Party (GLP).    Photo: zvg/fotozug.ch
David Meyer visualises his idea for a technical purification system.             Image: zvg/zuger-see-initiative.ch
 

He acquired his expertise through his management position as a wastewater engineer at a sewage treatment plant. "I'm an expert in this field," he adds. He also recently visited the IFAT environmental trade fair in Munich, and drew inspiration from it.

He is temporarily ending his political career.
But why does that David Meyer assess the situation so differently from the experts at Eawag? He says: "They are researchers; their profession involves measuring and analysing, but they are not engineers who create solutions. It's possible that they haven't progressed as far in their search for a solution." He finds it courageous that the canton would even allow the lake aeration, because, according to him, the pollutants would "simply be stirred up, instead of being removed."

His resignation from the Green Liberal Party (GLP) is also related to the initiative. "The party has its own priorities. I want to primarily focus my energy on the initiative," he explains. The issue has a certain urgency, as the aeration project could soon become relevant again. He also suspects that an initiative by an independent candidate could appeal to more parties, and thereby offer better chances. He therefore intends to put his political career on hold for the time being after the initiative. “I’ve achieved a great deal and, after three terms in parliament, I would like to make time for other things.”

The canton disagrees
Roland Krummenacher, head of the Office for the Environment (Amt für Umwelt), puts Meyer's enthusiasm into perspective. He points out that the Eawag water research institute also investigated the treatment of the deep water, and considered it as an alternative to lake aeration. But large quantities of chemical precipitants would be required for the chemical treatment. Furthermore, technically complex processes would have to be employed. "Such processes have never been used in a larger lake," he writes. "In addition, considerable quantities of precipitated sludge would be produced, which would have to be disposed of. There is also the risk that the purification processes could lead to secondary contamination of the lake water with other trace substances."

Roland Krummenacher further explains that, through aeration, the substances would be removed from Lake Zug "in a regulated, slow, and controlled manner". "The additional burden on the water quality in the Lorze and Reuss rivers, as well as in the groundwater along these rivers, is thereby minimal," he writes. Monitoring water quality at various locations would ensure "that the legal requirements for drinking water are not exceeded." The planned lake aeration would also accelerate the natural discharge of PFAS from Lake Zug via the Lorze River. "Actively removing PFAS from the lake water is not feasible with a reasonable amount of effort."

David Meyer, however, is confident that he can collect the 2,000 signatures. "The support from the public and from political figures is already very promising," he says.