Bringing back in life a part (15%) of Europe’s historical wetlands, on locations where farmlands are projected to be abandoned by 2040, would cut the riverine nitrogen load by 22%. This would enable major rivers such as the Rhine, Elbe and Vistula to meet water quality targets with minimal agricultural impact, a new JRC study shows. The findings also show that the benefits of restoration can outweigh the costs of restoration.
Published in Nature Water, the study highlights the crucial role of both existing wetlands and targeted wetland restoration as highly effective, nature-based solutions to combat nitrogen pollution and enhance water quality across Europe.
Pervasive nitrogen pollution
Europe continues to face extensive nitrogen pollution of its rivers and seas primarily stemming from widespread usage of agrochemicals like inorganic fertilisers, livestock waste, wastewater disposal and the deposition of atmospheric nitrogen from the combustion of fossil fuels.
Alarmingly, at EU level, 36% of rivers and 32% of lakes, 31% of coastal and 81% of marine waters have been reported as eutrophic, highlighting a critical and ongoing struggle to achieve good ecological status. This pervasive pollution not only threatens aquatic ecosystems but also results in devastating "dead zones," harmful algal blooms, and a troubling loss of biodiversity.
Furthermore, it exacerbates water scarcity issues by making water sources unsafe for human and environmental use. The difficulties persist despite the implementation of robust EU legislation including directives such as the Urban Wastewater Treatment Directive (91/271/EEC), the Nitrates Directive (91/676/EEC), as well as the Water Framework Directive (2000/60/EC), and the Marine Strategy Framework Directive (2008/56/EC).
The challenges underscore the urgent need for innovative and effective solutions to protect and restore Europe's vital water resources, a need systematically addressed by the European Water Resilience Strategy which was adopted in June 2025.
Leveraging the power of current wetlands
There is a growing interest in leveraging wetlands to enhance water quality, particularly in reducing nitrogen loading to downstream waters. Acting as natural filters, wetlands are exceptionally effective at removing excess nutrients such as nitrogen from both water and soil. The research, which covers the territory of the EU, Albania, Bosnia-Herzegovina, North Macedonia, Norway, Switzerland, Serbia, and the UK, including about 2.6 million wetlands (>300,000 km2), indicates that existing European wetlands currently remove approximately 1,092 kilotons of nitrogen annually.
This means the nitrogen loads entering the sea would be 25% higher without the wetlands. Preserving these existing ecosystems is fundamentally important, especially in regions with high nitrogen surplus, as their loss would significantly worsen water quality.
A lost potential
Since the onset of the industrial revolution, wetlands have been extensively drained, dredged, and filled to make way for agriculture and urban development. Europe emerges as a significant hotspot for wetland loss, having seen a dramatic reduction of approximately 70% of its historical wetlands. The loss equates to around 78.4 million hectares — an area roughly twice the size of Germany — with countries like Ireland, Lithuania, Czechia, Hungary, Italy, Finland, and Germany losing over 75% of their historical wetland areas.
The study considers a highly effective approach to wetland restoration that could further reduce nitrogen loads by up to 36%, thereby enhancing water quality across the continent. This could be achieved by restoring 27% of wetlands historically drained for agriculture (representing 3% of Europe’s land area), targeted in high nitrogen input areas. However, this could impact agricultural productivity in many areas.
A more targeted strategy involves the restoration of wetlands on farmlands projected to be abandoned by 2040. This approach would restore about 15% of the historical wetland drained and is estimated to achieve a 22% reduction in nitrogen loads while minimising the impact on agricultural productivity.
Strategic spatial targeting
The extent of restoration and the associated reductions in nitrogen load varied across different river basins, primarily due to spatial mismatches between nitrogen surplus hotspots and historically drained areas . For instance, the Rhine River basin presents more promising restoration opportunities compared to the Rhone basin. This is because many of its sub-basins feature a combination of high nitrogen surplus inputs and substantial areas of lost wetlands, providing ample opportunities for ecological recovery.
Similarly, the Elbe, Oder, and Vistula river basins also meet these critical conditions, offering some of the best prospects for successful restoration efforts.
This targeted approach to restoration ensures that environmental objectives are met while simultaneously considering economic and social factors, allowing sustainable agricultural practices to coexist with ecological restoration efforts.
Costs and benefits
While nitrogen load reduction through wetland restoration carries considerable costs, which vary based on wetland type and previous land use, the potential benefits are substantial. The environmental damages from reactive nitrogen in Europe are estimated at EUR 70-320 billion annually. The cost-benefit analysis presented in the research estimates the costs of restoration scenarios to amount from EUR 17-358 billion per year based on the scenario chosen.
Beyond nitrogen reduction, wetlands offer valuable ecosystem services such as carbon sequestration, coastal protection, groundwater regulation, flood control, biodiversity support, and water quality enhancement. When these benefits are considered, they can outweigh the costs of restoration.
Key recommendations
Leveraging these insights and adopting a strategic, targeted approach to wetland restoration will be vital in achieving sustainable water management and environmental resilience, ensuring a healthier future for the continent’s ecosystems and its people. European policymakers can deliver significant improvements in water quality by:
- Prioritising wetland conservation: safeguarding existing wetlands is fundamental to current water quality and provides a foundation for future restoration efforts.
- Embracing targeted restoration: strategic spatial targeting of wetland restoration in areas with high nitrogen surplus is critical to maximising effectiveness and cost-efficiency in meeting water quality targets.
- Integrating existing policies: leverage existing EU policies such as the European Green Deal, the Nature Restoration Regulation (NRR), and the Common Agricultural Policy (CAP) to support wetland restoration, aligning with the European Water resilience strategy's call for maximising the use of CAP Strategic Plans for water resilience. For instance, supporting farmers to restore habitats on fallow land through payment for ecosystem services (PES) schemes can foster a green transition and achieve multiple environmental goals simultaneously.