Overview of monitoring networks
The FOEN operates and coordinates several monitoring networks on the topic of water. Long-term measurements at permanent gauging stations and individual readings at temporary sites enable the FOEN to keep track of water flow and quality in Switzerland’s rivers and groundwater, as well as the water level in its lakes.
Basic monitoring network: water levels and discharge in surface waters
The FOEN Hydrology Division’s basic monitoring network now comprises some 260 gauging stations on surface waters. In addition to lake water levels, river discharge is measured at 200 sites.
The Monitoring Network of Sediment in bodies of water
The FOEN operates a nationwide network to monitor the transport of sediment in bodies of water. This involves measuring the concentration of suspended load and turbidity in watercourses, as well as recording quantities of bed load material collected in selected traps. Data from these measurements can be obtained from the FOEN. In previous years, river deltas were also surveyed. Within pilot projects, suspended loads are additionally analysed for various chemical and physical parameters, including heavy metals and microplastics.
Watercourse temperatures
Water temperature is one of the key physical parameters that determines chemical and biological processes in a watercourse. The FOEN’s measurements are the basis for monitoring temperature changes and understanding their causes.
Lake water temperature
As a result of climate change, the water temperature of many lakes has risen in recent decades. A further increase is expected. The warming affects the mixing dynamics and thus the oxygen content in the deeper layers of the lakes. Since 2025, data has been collected at various Swiss lakes for long-term monitoring of water temperature and other parameters, measured continuously at both federal and cantonal levels.
National Surface Water Quality Monitoring Programme (NAWA)
In order to be able to assess the condition waterbodies in Switzerland over time, data must be regularly collected and documented. The FOEN, in cooperation with the cantons, provides this basis with the National Surface Water Quality Monitoring Programme (NAWA). National monitoring programme for loads of substances in swiss watercourses (NAWA FRACHT) is a long-term federal sub-programme in which the two federal research institutes Eawag and WSL monitor the state of rivers on the basis of their substance loads.
Bathing water quality
Virtually all rivers and lakes in Switzerland are safe to swim in, in terms of water quality. Thanks to various protective measures and major advances in wastewater treatment in recent decades, the water in Swiss rivers and lakes is now very clean.
NAQUA National Groundwater Monitoring
The NAQUA National Groundwater Monitoring provides a nationally representative picture of the situation and development of the groundwater resources in terms of both quality and quantity.