State of waterbodies

As Europe’s water tower, Switzerland has substantial water resources. Despite the generally good quality of its water, residues from fertilizer and plant protection products, micropollutants, man-made structures and artificial obstacles damage its surface and underground waters. Analyses and predictions of water levels and flows make it possible to issue early flood warnings.

Swiss water balance


The water balance includes the main components of the water cycle. The FOEN calculates the water balance for Switzerland and its large river basins every year.


Water flow & flow regime

In principle, Switzerland has a large water supply that depends on natural factors such as weather conditions or glaciation. However, the volume of water in watercourses is influenced by hydropower production in many areas (residual flow, hydropeaking). In the future, water availability will be limited regionally during dry periods as a result of climate change. The FOEN is monitoring the water flow and flow regime of Swiss bodies of water.


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.

Water quality

Water quality in watercourses has improved significantly since the 1970s in terms of nutrient pollution. Micropollutant contamination is the new and biggest challenge at this time.

Structure and morphology

Swiss watercourses are heavily developed with control structures and their natural functions are limited. Around half of the watercourses located at elevations of up to 600 metres above see level are in poor morphological condition and have many obstacles that impede the migration of fish.

Bed load and suspended solids

Sediment is an important component of ecologically intact rivers and streams. However, the sediment budget is disrupted in around one-third of watercourses. The FOEN monitors the transport of sediment by watercourses across Switzerland.



The FOEN measures the current water levels of Swiss lakes, makes predictions and informs the public.


The development of wastewater treatment and the application of new wastewater technologies, not to mention agricultural measures, have substantially lowered nutrient and pollution loads in lakes. However, there is increasing pollution from synthetic organic trace compounds that are not readily biodegradable.


Groundwater resources

Switzerland is rich in groundwater. Groundwater resources occur almost everywhere, both in unconsolidated sediments and fissured or karstified bedrock. They represent an important natural and economic resource.

Groundwater quantity

Groundwater levels and spring discharges indicate the status and trend of groundwater quantity conditions. Variations in groundwater quantity are heavily influenced by precipitation and temperature on the surface of the soil.

Groundwater quality

Groundwater does not naturally contain any persistent synthetic substances. Nitrate and residues of plant protection products have a long-lasting adverse impact on groundwater quality. Along watercourses, micropollutants from industry, commerce and households are also found in groundwater.

Groundwater temperature

The temperature of groundwater is one of its most important characteristics, and a key factor influencing its hydrochemical and biological state. It affects the dissolved oxygen content of the water, as well as the degree of mineralisation. Changes in groundwater temperature over time can highlight potential impacts of climate change and urbanisation on groundwater quantity and quality.

Stable water isotopes

The stable water isotopes deuterium and oxygen-18 are suitable tracers in the water cycle and can also be used to track climate changes.

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.


Quality of the forecasts

The FOEN uses several hydrological models for its forecasts. The water level and discharge forecasts are based on hydrological and meteorological data and hydrological models.
The quality of the hydrological forecasts is affected by various factors such as the size of the catchment and its hydrological complexity, and by the weather conditions.

Further information

Last modification 30.12.2019

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