Groundwater Nitrate Levels in Aare Valley
NAQUA monitoring data revealing persistent nitrate contamination above 25 mg/L in 40% of Aare Valley groundwater wells, with agricultural runoff identified as primary source.
Provenance
Legal Citation
FOEN. (2024). NAQUA National Groundwater Monitoring: Aare Valley Stations Bulletin 2024. Retrieved from https://opengovclimate.ch/en/evidence/groundwater-quality-aare/
Location
Measurement Period
The NAQUA national groundwater monitoring network recorded persistent nitrate contamination in the Aare Valley throughout 2024. Of the 15 monitored wells, 40% (6 wells) exceeded the federal quality criterion of 25 mg/L NO3 established in GSchV Annex 2.
Key Findings
- Wells exceeding limit: 6 of 15 (40%) above 25 mg/L NO3
- Maximum concentration: 62 mg/L at Koppigen station
- Annual mean (all stations): 28.4 mg/L
- Trend: +3.2% year-over-year increase since 2020
- Primary source: Agricultural runoff (intensive crop cultivation)
Legal Significance
Under GSchG Art. 22, authorities must ensure groundwater quality meets the requirements of GSchV Annex 2. The persistent exceedance — affecting 40% of wells — may constitute a violation of water protection obligations. Under GSchG Art. 27, cantons must designate protection zones and restrict activities that impair groundwater quality.