The survey conducted by the Department of Water and Energy shows that chemicals are endangering streams in the canton of St. Gallen

Quality criteria for pesticides, drug residues or industrial chemicals are in some cases largely exceeded in the watercourses of St. Gallen. This is confirmed by the latest measurement campaign of the Office of Water and Energy.

Adrian Lemmenmeier

Cantonal experts take water samples with this device. Here in Äaeeli in the municipality of Rheintaler Au. (Photo: PD)

Cantonal experts take water samples with this device. Here in Äaeeli in the municipality of Rheintaler Au. (Photo: PD)

The Office of Water and Energy of the Canton of St. Gallen examined five sources of oxides such as pesticides, drugs and industrial chemicals. the The result is sobering: on all water courses, the quality criteria of the problematic substances were exceeded during most of the observation period from April to the end of October 2018. And massive – in the extreme case by a factor of 160.

Small streams can therefore be contaminated with toxic chemicals throughout the township, according to the findings of the Water Quality Department of the Office of Water and Energy. . "We were surprised by the fact that even the water courses whose use in agriculture or industry is not particularly intensive in the catchment area have high values, "said Vera Leib, head of the department.

Smaller quantities can be deadly

Water quality was examined in Lattenbach and Wagnerbach in Rapperswil-Jona; in the side ditch and in the reservoir ditch at Benken and in the Äächli of the municipality of Au. Of the 109 substances analyzed, 74 belong to the group of pesticides, probably from agriculture or gardens. Vera Leib says:

"With insecticides, even the smallest amounts can be toxic or lethal to the stream's organisms."

This reduces the livelihoods of larger animals such as fish. In addition, some toxins would be transmitted throughout the food chain. Perfluorooctane sulfonate (PFOS), for example, which usually reaches sewage treatment plants in the water, is also detectable in the body of piscivorous birds. This substance has been systematically detected in Wagnerbach Bach at a high concentration. PFOS has been largely banned in Switzerland since 2011. However, it occurs in fire-fighting foams before the ban and is approved for certain industrial processes. "We now want to know, after the measurements, how and where the substance enters the water course," Leib said.

How dangerous is the pollution of water courses for humans? "In principle, trace substances can reach groundwater," Leib said. Some would be tied to the ground, others would infiltrate. "The groundwater studies in the canton of St. Gallen are not, however, of concern." Even previous results of studies on micropollutants in the body of fish are harmless. "However, pollution is endangering the intact ecosystem of a water course." And it is important, especially for the quality of the water.

"After the treatment plant, rivers and streams clean the water, but only healthy waters can do it."

Better educate farmers

An important part of the chemicals present in the water courses of the Canton of St. Gallen comes from agriculture. The canton therefore wishes to sensitize farmers to the problem in cooperation with the agricultural center of Salez and the farmers' association. "Farmers have improved pesticide handling in recent years," said Peter Nüesch, president of the Eastern Switzerland Farmers Association. "But the county's study shows that this is not enough."

Farmers should be more aware of the problem and show how important it is, for example, to handle crayfish in the vicinity of the water with special care. To this end, the first training courses took place at the agricultural center of Salez. The Nüesch continues:

"But high food quality requires plant protection products."

You will not be able to do without their use. "Farmers are becoming more sensitive about it."

This should not be enough for environmentalists. At the national level, two initiatives on the use of pesticides are underway. The so-called drinking water initiative only wants to subsidize farmers who do not use pesticides. The initiative on pesticides aims to completely ban the use of synthetic pesticides. The National Council rejected both initiatives at the end of June. Without counter-proposal.