Nutrients in freshwater in Europe

Indicator Assessment
Prod-ID: IND-8-en
Also known as: CSI 020 , WAT 003
Created 04 Oct 2019 Published 03 Dec 2019 Last modified 03 Dec 2019
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, which has been more or less stable since 1997, although it has decreased since 2014 and is currently closer to the 1992 level. On average, the nitrate concentration in European rivers decreased by 0.02 milligrams per litre of nitrogen (mg N/l) per year (0.8 % per year) between 1992 and 2017, but the concentration has levelled off since around 2010. This 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. The average phosphate concentration in European rivers has decreased markedly over the last two-three decades (by 0.002 milligrams per litre of phosphorous (mg P/l) per year (1.6 % per year). The average total phosphorus concentration in lakes also decreased over the period 1992-2017 (0.0004 mg P/l per year (0.9 %)). The decrease in phosphorus concentration is likely related to improvements in waste water treatment and the reduction of phosphorus in detergents.

Key messages

  • Nutrient conditions in European surface waters have improved over recent decades. However, there has been no overall decrease in the nitrate concentration in groundwater, which has been more or less stable since 1997, although it has decreased since 2014 and is currently closer to the 1992 level.
  • On average, the nitrate concentration in European rivers decreased by 0.02 milligrams per litre of nitrogen (mg N/l) per year (0.8 % per year) between 1992 and 2017, but the concentration has levelled off since around 2010. This 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.
  • The average phosphate concentration in European rivers has decreased markedly over the last two-three decades (by 0.002 milligrams per litre of phosphorous (mg P/l) per year (1.6 % per year). The average total phosphorus concentration in lakes also decreased over the period 1992-2017 (0.0004 mg P/l per year (0.9 %)). The decrease in phosphorus concentration is likely related to improvements in waste water treatment and the reduction of phosphorus in detergents.

Are nutrient concentrations in Europe's freshwaters decreasing?

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
There was a slight increase in average annual mean nitrate concentration in European groundwater between 1992 and 1997. Since then the average concentration has been more or less stable, but it has decreased since 2014, and in 2017 it was closer to the 1992 level. In order to include more groundwater bodies, and thus be more representative, aggregated time series have been calculated for 2000-2017 (the shorter time series) as well as for 1992-2017 (the longer time series). The shorter time series follows the longer one closely and, because of the recent decrease, the average concentration in 2017 was lower than at the start of the time series in 2000. 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 there are similar numbers of increasing and decreasing trends across Europe. 

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 trend for the time period 2000-2017 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 is the largest contributor of nitrogen pollution and, 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 nearly halved over the period 1992-2017, and in many rivers this decrease started in the 1980s. The marked decline is also evident for the time period 2000-2015 but contrary to the nitrate results, the average concentration is somewhat higher when using the larger, more representative set of river sites. There is also a tendency for the concentrations to level off and this is stronger for the shorter time series. The decrease in river phosphate can be related to the measures introduced by national and European legislation, in particular the Urban Waste Water Treatment Directive [2], 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 sharp as the reduction of 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.


Are nitrate concentrations in Europe's groundwater decreasing?

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). Between 2015 and 2017, 15 out of 25 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, 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, Czechia, Denmark, Finland, France, Poland, Portugal, Serbia and Slovakia. Groundwater nitrate concentrations were generally low (more than 80 % of GWBs having less than 10 mg NO3/l) in Croatia, Estonia, Finland, Iceland, Latvia, Lithuania and Sweden. Overall, about half the GWBs included in the analysis belonged to this concentration class.

Trends in groundwater nitrate concentration (see Fig. 2)

There was a slight increase in average annual mean nitrate concentration in European groundwater between 1992 and 1997. Since then the average concentration has been more or less stable, but it has decreased since 2014, and in 2017 the level was closer to that of 1992. 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 33 % of the GWBs have shown decreasing nitrate concentrations since 1992 and a further 33 % have shown increasing concentrations. For the shorter time series starting in 2000, there were slightly more decreasing (28 %) than increasing trends (26 %) but the proportion of GWBs with no trend was somewhat higher (46 %). The countries with the highest proportion (30-60 %) of GWBs with significant decreasing trends since 1992 were Austria, Finland, France, Ireland and Portugal. 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 significant increasing trends were Belgium, Denmark, Estonia, Germany, and Lithuania (one GWB only)  (37-100 %) for the longer time series and Cyprus, Czechia and Malta (31-100 %) for the countries with only the shorter time series.


Are nutrient concentrations in Europe's surface waters decreasing?

Nitrate in rivers in Europe

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