A new Nature Communications study reveals that around half of European rivers and streams are affected by salinisation, while more than 23,000 km of the river network (around 2%) exceed 1 mS/cm, a salinity level well above available international standards for the protection of aquatic life.
Carried out by an international team of scientists, including researchers from the JRC, the study provides a scientific basis for strengthening the monitoring and management of freshwater salinisation across Europe.
Freshwater salinisation across Europe results from both natural factors and human activities. Climate, geology and hydrology influence river salinity, while human footprint and land-use change are strongly associated with increased salinisation, underscoring the importance of managing anthropogenic pressures.
This phenomenon can have far-reaching ecological and societal consequences. Higher levels of salinity reshape aquatic communities, threaten biodiversity and undermine the very resources that sustain human life – drinking water, irrigation for agriculture and water for industry.
How common is freshwater salinisation in Europe?
So far, most studies have examined salinisation at local or regional levels. This new research analysed river data spanning 35 European countries using the GlobSalt database, covering water quality records from 1970 to 2024. It found that, in 28 out of the 35 countries analysed, there are rivers where salinity has more than doubled compared with estimated natural background conditions.
Salinity was assessed using electrical conductivity (measured in mS/cm), a widely used proxy for salt concentrations in freshwater.
Around half of the European river network is affected by salinisation, with 26% classified as low level, 14% as moderate, 9% as severe, and 1% as extreme. The analysis also found that salinity exceeds drinking water limits in around 1% of the river network, and irrigation and industrial water quality limits in around 3%.
While well-documented hotspots exist in countries such as Germany, Poland and Spain, the study also identifies previously underreported hotspots, particularly in Romania and Hungary.
Background
While recognised as a growing pressure on European freshwater ecosystems with mounting ecological and socioeconomic impacts, salinisation remains largely overlooked in existing EU and national water policies.
Twenty-five years after the adoption of the EU Water Framework Directive (WFD), which requires Member States to achieve “good ecological and chemical status” for surface waters, most countries still lack dedicated salinity standards and do not systematically monitor or report on salinity impacts.
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