Indicator Assessment

Nutrients in freshwater in Europe

Indicator Assessment
Prod-ID: IND-8-en
  Also known as: CSI 020 , WAT 003
Published 09 Dec 2020 Last modified 11 May 2021
27 min read
  • Nutrient conditions in European surface waters have improved over recent decades. However, there has been no overall decrease in the nitrate concentration in groundwater.
  • The average phosphate concentration in European rivers has decreased markedly over the last two or three decades (by 0.002 milligrams per litre of phosphate-phosphorous (mg P/l) per year (1.3 % per year). The average total phosphorus concentration in lakes also decreased over the period 1992-2018 (0.0003 mg P/l per year (0.8 %)). The decrease in phosphorus concentration is likely related to improvements in waste water treatment and the reduction of phosphorus in detergents. However, as for nitrate in rivers there is a tendency for concentrations to level off in recent years, especially for rivers.
  • On average, the nitrate concentration in European rivers decreased by 0.01 milligrams per litre of nitrate-nitrogen (mg N/l) per year (0.02 % per year) between 1992 and 2018, but the concentration has levelled off since around 2010. The decrease is likely related to effects of measures to reduce agricultural inputs of nitrate and improvements in waste water treatment. However, the apparent stabilisation of river nitrate concentrations in recent years may call for further measures to be taken.

Updated with 2018 data and text revised accordingly

Nutrient trends in European water bodies

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Groundwater - nitrate
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Rivers - nitrate
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Rivers - phosphate
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Lakes - phosphorus
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Nitrate in groundwater

The average annual mean nitrate concentration in European groundwater has been relatively stable since 1992. In order to include more groundwater bodies, and thus be more representative, aggregated time series have been calculated for 2000-2018 (the shorter time series) as well as for 1992-2018 (the longer time series). The shorter time series follows the longer one closely, but the concentration level is slightly higher. The lack of a marked trend at European level does not imply that there are limited changes in groundwater nitrate concentrations overall, but rather that the numbers of increasing and decreasing trends across Europe are quite similar. 

Nitrate in rivers

At European level, the average river nitrate concentration decreased steadily over the period 1992-2009 but has varied around the same average level since then. The time series for the time period 2000-2018 is parallel to the longer time series, but the concentration level is lower. As the shorter time series includes more monitoring sites, this lower level is more representative of the nitrate conditions in European rivers. Agriculture contributes most to nitrogen pollution but, thanks to the EU Nitrates Directive [1] and national measures, nitrogen pollution from agriculture has been reduced in some regions over the last 15-20 years. This reduced pressure is reflected in lower river nitrate concentrations. However, the apparent stabilisation of river nitrate concentrations in recent years may call for further measures to be taken.

Phosphorus in rivers

The average concentration of phosphate in European rivers more than halved over the period 1992-2012, and in many rivers this decrease started in the 1980s. The marked decline is also evident for the shorter time series, but contrary to the nitrate results, the average concentration is somewhat higher when using this larger, more representative set of river sites. Concentrations also tended to level off and even increase slightly at the end of the time period. The decrease in river phosphate over much of the time period can be related to the measures introduced by national and European legislation, in particular the Urban Waste Water Treatment Directive, which involves the removal of nutrients. Also, the change to phosphate-free detergents has contributed to lower phosphorus concentrations.

Phosphorus in lakes

Over recent decades, there has been a gradual reduction in total phosphorus concentrations in many European lakes, although it has not been as marked as the reduction in phosphate in rivers. Again, the concentration level is higher for the shorter, more representative time series. As the treatment of urban waste-water has improved, the amount of phosphorus in detergents has been reduced, many waste water outlets have been diverted away from lakes, phosphorus pollution from point sources has gradually become less significant and the total phosphorus concentration in lakes has declined. However, diffuse runoff from agricultural land continues to be a major source of phosphorus in many European lakes. Moreover, phosphorus stored in sediment can keep lake concentrations high and prevent the improvement of water quality despite a reduction in inputs.

Nitrate in groundwater in Europe

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Current concentrations per country

Groundwater nitrate concentrations mainly reflect the relative proportion and intensity of agricultural activity (see Nitrate in groundwater). In the period 2016 to 2018, 16 out of 28 countries had groundwater bodies (GWBs) with an average nitrate concentration above the EU Groundwater Quality Standard of 50 milligrams of nitrate per litre (mg NO3/l), as laid down in the Groundwater Directive [3]. Belgium, Bulgaria, Cyprus, Czechia, Germany, Malta (two GWBs only), and Spain had the highest proportion (more than 10 %) of GWBs with an average concentration above the standard, but there were also GWBs above the standard in Austria, Denmark, Estonia, France, Italy, the Netherlands, Poland, Portugal, and Slovakia. Groundwater nitrate concentrations were generally low (more than 80 % of GWBs having less than 10 mg NO3/l) in Albania, Croatia, Estonia, Finland, Iceland (one GWB only), Latvia, Lithuania, and Sweden. Overall, nearly half the GWBs included in the analysis belonged to this concentration class.

Trends in groundwater nitrate concentration (see Fig. 2)

The average annual mean nitrate concentration in European groundwater has been relatively stable since 1992. However, in recent years there has been a slight increase. Using the filter in Figure 2, the groundwater nitrate time series for individual countries can be illustrated.

The apparent lack of an overall trend in nitrate concentrations in European groundwater is because of opposing trends for individual GWBs (see Groundwater - nitrate - trend analysis). A total of 29 % of the GWBs have shown decreasing nitrate concentrations since 1992 and a further 30 % have shown increasing concentrations. For the shorter time series starting in 2000, there were also slightly fewer decreasing (23 %) than increasing trends (25 %) but the proportion of GWBs with no trend was somewhat higher (51 %). The countries with the highest proportion (38-55 %) of GWBs with significantly decreasing trends since 1992 were Austria, Finland, Ireland, Portugal, and Slovakia. From the larger selection of countries with time series from 2000, Czechia and Switzerland also had a high proportion of decreasing trends. The countries with the highest proportion of GWBs with significantly increasing trends were Belgium, Bulgaria, Denmark, Germany, and Slovenia (33-45 %) for the longer time series and Cyprus, Czechia, and Serbia (34-43 %) for the countries with only the shorter time series. In terms of size of the trends, the largest average relative change over the whole time period was found where there was an average increase in concentrations. The largest increase was observed for Denmark (stabilised in the latest decade) and Serbia (higher concentrations 2015-2017).

Nitrate in rivers in Europe