Swiss watercourses: great need for action
The biological status of Swiss watercourses is partly insufficient. This is shown by the first results of the national monitoring of surface waters by the FOEN. While the load of phosphorus and nitrate has decreased, that of micropollutants is increasing.
The first-time Results of the national monitoring of surface waters (NAWU) reveal a varied picture of the condition of watercourses: pollution with phosphorus and nitrate has decreased, but that with micropollutants is increasing, and the biological condition shows considerable deficits in some cases. According to Marc Chardonnens, Director of the Federal Office for the Environment (FOEN), these findings confirm that there is a great need for action to restore and maintain water quality.
NAWA is the monitoring program for the holistic investigation of the state of water bodies, which is carried out jointly by the federal government and the cantons. These biological and chemical-physical investigations provide an overall view for the first time.
Less phosphorus and nitrate
Thanks to the construction of wastewater treatment plants, water quality has improved considerably since the 1980s. Significantly less nitrate and especially phosphorus enter the water bodies. Pollution levels in small and medium-sized watercourses, into which large quantities of treated wastewater are discharged or numerous nutrients from agriculture enter, are still too high. Excessive nutrient concentrations can cause rivers and lakes to suffocate.
More than 230 micropollutants detected
Micropollutants pose a problem for water quality. In 2012, over 230 different micropollutants were detected in a systematic study of five medium-sized watercourses representative of the Central Plateau. The partly high concentrations measured are not dangerous for humans. However, they indicate that they are partly responsible for the deficits in biodiversity that were found in the water bodies.
Deficits in biological condition
To measure the quality of water bodies as habitats, four categories of living organisms were studied. Based on the composition and density of invertebrates and aquatic plants, the biological status was rated as good to very good at two-thirds of the monitoring sites. Thus, the quality of the aquatic ecosystem is significantly impaired at at least 30 percent of the monitoring sites considered. In the case of fish, however - which have higher demands on habitat quality - the findings are even worse: the quality of the water body was good to very good at only one third of the monitoring sites, and a full two thirds were impaired.
These results confirm that there is a need for action to improve both the status of watercourses and their resilience, namely in view of climate change and its negative consequences for aquatic ecosystems.
Extensive work in the coming decades
Only in a good condition can water bodies fulfill all their functions, be it as drinking water suppliers, as local recreation areas for the population or as habitats for plants and animals. Special attention must be paid to small watercourses. They account for 75% of the water network and are important for biodiversity.
Extensive work to reduce micropollutants and renaturalize water bodies has already begun. To reduce micropollutants, Parliament has given the go-ahead for upgrading specifically selected wastewater treatment plants. They are to receive an additional treatment stage for the elimination of trace substances in wastewater. To prevent micropollutants from agriculture, measures must be taken at the source. An action plan for risk reduction and sustainable use of plant protection products is currently being drawn up under the leadership of the Federal Office for Agriculture (FOAG). It was sent out for consultation on July 5, 2016.
In parallel with the reduction of pollutant inputs, watercourses must also become more natural. According to the Water Protection Act, the cantons, with the support of the federal government, must revitalize 4000 of the total 15,000 kilometers of watercourses that are in poor condition by the end of this century. In addition, the negative consequences of hydropower utilization (e.g. fish migration obstacles or artificial discharge fluctuations) must be eliminated by 2030. Other measures, such as the designation of watercourse areas, are already underway.
