Ecologically intact water bodies will be better able to cope with climate change and meet the diverse demands of society. It is therefore important to protect water resources from excessive abstraction and from contamination by pollutants and fertilisers. In addition, streams, rivers, lakes and groundwater must be kept in, or restored to, a state that is as natural as possible.
With climate change, the Swiss waste-water treatment plants (WWTPs) system will reach its limits: if low water flows in rivers mean that the effluent from WWTPs is less diluted, releasing even treated waste water will cause too much pollution in water bodies.
It is therefore important that the volume of pollutants from settlements entering waters is lowered still further. To reduce the chemical pollution of rivers receiving a high proportion of waste water, by 2040 approximately 140 strategically chosen WWTPs are to be adapted to include additional treatment stages.
Intense rainfall events are set to increase. These events result in so much water flowing into the sewer system that WWTPs can no longer process it, meaning that some untreated waste water ends up in rivers. To avoid this, steps should be taken in the future to prevent as much rainwater as possible from sealed surfaces from entering the sewer system. Instead, there must be more systematic attempts to infiltrate or retain it within settlements.
Reaction of separation and combined systems to heavy rainfall
Pollutants from agriculture
Another challenge facing water bodies is the input of pollutants from agriculture: residues of pesticides and fertilisers end up in groundwater, rivers and lakes, affecting drinking water supply and aquatic ecology in many places. The increase in heavy precipitation will enhance the runoff of nutrients and pollutants from fields into waters, and higher levels of winter precipitation will transport more nitrate from fertilisers into groundwater. It is therefore vital to reduce the amount of pollutants being applied. This is the aim of the federal government’s Plant Protection Products Action Plan launched in 2017.
Water abstractions for settlements, industry/commerce and agriculture are widespread in Switzerland, targeting groundwater as well as rivers and lakes. By far the most significant in terms of quantity are the approximately 1,500 abstractions by hydropower plants. The Waters Protection Act regulates how much water must remain in bodies of water below the point of withdrawal, thus preventing them from partially or completely drying up.
Wetlands, as well as many streams and rivers, require sufficiently high groundwater levels to prevent them from drying out or running too low during a drought. Economical use of groundwater abstraction is therefore a necessity.
Renaturing water bodies
In Switzerland, obstacles in watercourses also considerably limit the mobility of numerous aquatic organisms. Hydropower plants and weirs, for example, hinder or entirely prevent the migration of fish and other animals such as crayfish. Some 16,000 kilometres – around a quarter of all the country's waterways – have now been structurally impaired or even channelled into underground pipes.
As part of the 2011 revised Waters Protection Act, Switzerland launched two long-term projects to rehabilitate watercourses:
- By 2030, fish migration should be improved at some 1,000 weirs, excessive discharge fluctuations (hydropeaking) will be eliminated at around 100 hydropower plants and 500 installations that cause bedload deficits will be remediated.
- In addition, work has begun throughout the country to restore more space and naturalness to some 4,000 kilometres of watercourses by 2090 and to provide better shading.
Ecological restoration and renaturation will make aquatic life more resilient to climate change, but they will also help to enhance wildlife connectivity and the beauty of the landscape. However, climate change mitigation measures are just as important in order to keep the rise in water temperatures and changes in flow rate as small as possible.
Measures to strengthen surface water bodies
The report ‘Effects of climate change on Swiss waters’ gives a concise overview of the results and is a gateway to further technical information and data.
Last modification 14.05.2021
Federal Office for the Environment FOEN