27.06.2019 – 10:05 pm
In Bern, the National Council discussed pest-pesticides in drinking water. Zurich focuses on other chemicals.
The two initiatives aim at better protection of drinking water from foreign substances. The ban on the use of pesticides is intended to completely ban synthetic pesticides. The Drinking Water Initiative calls for subsidies to be paid only to farmers who refrain from pesticides and preventive use of antibiotics. In agriculture, various chemicals are used to protect fruit and vegetables from diseases and insects. The remnants of these resources can be found in every fifth drink of potable water. This has been shown by the federal government study.
The city of Zurich receives most of the drinking water from Lake Zurich. This is by the Water, Energy and Air Office (Awel) only slightly contaminated with pesticides. "Active ingredients, if present, can only be detected in the range of several billion of grams per liter," says Isabelle Rüegg from Canton Baudirectional Press Office. As for pesticide degradation products, the difference between seawater and groundwater is even more pronounced, says Rüegg. "In Lake Zurich, these products of degradation are unmistakable."
Up to 100 times the concentration
Drinking water from Lake Zurich is considerably less contaminated than pesticides than drinking water from groundwater basins in Mittelland, says Marianne Locher, Public Relations Manager at Wasserversorgung Zürich. In Mittelland, "more individual substances" and "10 to 100 times higher concentrations" were measured. The reason for the differences is high dilution in Lake Zurich caused by rain and dissolved water and relatively low agricultural use in its catchment area.
"At Lake Zurich, the focus is more on exposure to daily chemicals," says Locher. These are medicines, cosmetics and industrial chemicals that reach the lake through the treatment plant. In the lake, traces of cargo can be traced through settlements, roads and ship traffic, adds Awel. Drinking water quality is still very good. "Thanks to the multistage treatment of sea water, traces of impurities are effectively removed," explains Rüegg from Baudirektion.
Traces of pesticides in the tributaries
Traces of pesticides were discovered in the tents of Lake Zurich. Awel has reviewed some side streams and the River Ion between 2012 and 2017, says Rüegg. "Like in all areas where intensively cultivated agricultural areas can be found, excessive levels of pesticides have been discovered in some areas." Canton St. Gallen collected samples of Linth and his sub-tails monthly in 2016. In this process, most of the low concentrations of intakes from the sewage treatment plant were registered, according to the Water and Energy Office St. Gallen. "Pesticides play a subordinate role in these two waters." So far, the canton of Glarus has not found pesticides in ground water basins and surface waters. Canton Schwyz does not analyze pesticides.
"Lake Zurich has good overall quality," says Locher from the Zurich Water Supply. Thanks to a measurement program that lasts for 40 years, the Zürich water supply company is well aware of the state of the lake. The data would be shared with neighboring cantons, research institutes and other water utilities, says Locher. "In addition, plumbing in Zurich is committed to consistent water protection at the national level."
The National Council last week rejected the ban on pesticides and the drinking water initiative. SVP, CVP, GDP and parts of the FDP did not want to prepare an anti-bill. The counterattack is needed, among other things, by the Swiss water supply association, which also includes the city of Zurich. Compared to the NZZ, the deputy director of the association recently stated: "Without counterproductive, the drinking water initiative remains the only political option to strengthen drinking water protection." (David Herter and Pascal Wiederkehr / Photo: p.
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