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Swiss groundwater is contaminated with pesticides and fertilizers

A farmer fertilizes a meadow near Waldkirch in Canton St. Gallen. (Image: Ennio Leanza / Keystone)

A farmer fertilizes a meadow near Waldkirch in Canton St. Gallen. (Image: Ennio Leanza / Keystone)

Substances from agriculture affect groundwater "widespread and sustainable". This is stated by the federal government in a national investigation. The report is of political importance.

Angelica Hardegger

Water drives Swiss policy. Next year, the population will vote on the initiative "For clean drinking water and healthy food". Initiators deny the pollution caused by pesticides and fertilizers. But how much groundwater in Switzerland is actually polluted has not yet been cleared throughout the country. The latest results for the whole of Switzerland were published ten years ago. Now the Federal Environment Office (Bafu) is providing new insights.

The agency will release a groundwater status report this Thursday, which will help determine political debate over the coming months. The report is based on data from 2007 to 2014. More than 600 measuring points were sampled during this period. The result: groundwater in Switzerland is polluted, especially due to agricultural substances.

The main problem of over fertilization

Groundwater quality is compromised, Bafu writes. Agricultural foreign substances would "spread water and permanently" affect water. The biggest pressure is in Mittelland, where many people live and farmers intensively cultivate their fields and fields.

The main problem is over-fertilization. Swiss farmers produce more fertilizer in the fields than the plants can absorb. Excess nitrogen accumulates in the soil and enters groundwater as nitrate.

Water experts have detected more nitrates at 15 to 20 percent of measuring points than the Water Conservation Act allows. In agricultural fields, values ​​were temporarily at 40 percent above the legal maximum. The permissible value of drinking water is exceeded at 2 to 4 percent of the measuring points.

Pesticides contaminate water

Pesticides have also been detected in groundwater. At every other measurement site, the samples contained pesticide active substances or their degradation products, the so-called metabolites.

As with nitrates, the problem focuses on intensely managed lowlands. Experts have often found in her samples the metabolites of herbicides used in the cultivation of sugar beet and maize. For metabolites, the Water Conservation Act does not define maximum levels. However, they are often more mobile and lasting than the actual pesticide active ingredients, which have been detected in only a few (2014 in nine) places. The entry of metabolites into groundwater must be prevented or minimized, the report said.

Atrazine, a herbicide that has not been approved since 2007, has been widely reported. From the longevity of the material, Bafu concludes that it is even more important to "identify problematic events at an early stage." The federal government is currently reviewing another problem, the herbicide chloridazone. The European Union had its approval expired at the end of 2018. Switzerland should follow this by the end of the year.

Farmers politicians have repeatedly claimed that pesticide residues, including those from private gardens and green spaces, are reaching groundwater. The Federal Office of the Environment contradicts this description. "To a large extent, pesticides are only used in agriculture," the report said. On the streets, squares and private roads, herbicides have been banned from weeds since the 1990s.

Drinking water under pressure

Groundwater is the most important source of drinking water in Switzerland. Over 80 percent of drinking water is drawn from groundwater, often without treatment. Is drinking water in Switzerland dangerous?

No, the Federal Environment Office writes. Groundwater continues to supply "impeccable drinking water in sufficient quantities." However, the Environmental Protection Agency limits: "However, this is no longer obvious in itself: our most important drinking water resource is coming under increasing pressure."

Fewer animals, less manure

As early as spring, ETH researchers documented that small streams in the cultivated land were heavily contaminated with pesticides. They concluded that certain substances pose an "acutely toxic risk" to plants and animals in water.

Even peasant politicians now admit that there is a need to act on nitrates and pesticides. But as it should be done, the spirits have divorced. The drinking water initiative aims to reduce over-fertilization by drastically reducing livestock. Farmers should no longer receive state support if they keep more cows, chickens or pigs than they can feed on their own food. Even those using pesticides should forego direct payments.

The Federal Environment Office recommends less radical measures in the groundwater report. The authority calls for Swiss methods in agriculture. For example, regional projects have shown that less nitrates penetrate groundwater when soil only remains in winter.

In the case of pesticides, Bafu relies on a Plant Protection Action Plan. The authorities are also complaining to the cantons. Under federal law, they must leave groundwater protection zones, but they do not in many cases. Peasant politicians also repeatedly refer to this problem. But they are not completely innocent of the lack of protected areas: where they fail, they often fail because of farmers' resistance.