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Freshwater quality (SEBI 016) - Assessment published May 2010

Indicator Assessment Created 17 Sep 2009 Published 21 May 2010 Last modified 05 Feb 2015, 05:35 PM
Topics: ,

Generic metadata


Biodiversity Biodiversity (Primary topic)

water | biodiversity | csi
DPSIR: Pressure
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • SEBI 016
Temporal coverage:
Geographic coverage:
Albania, Austria, Belgium, Bulgaria, Czech Republic, Denmark, Estonia, Finland, France, Germany, Hungary, Ireland, Latvia, Liechtenstein, Lithuania, Luxembourg, Macedonia (FYR), Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, United Kingdom

Key policy question: What is the status of freshwater quality in Europe?

Key messages

Pollution of rivers with organic matter and ammonium is decreasing as are the levels of other anthropogenic nutrients in freshwater generally (rivers, lakes and groundwater). This reduces stress on freshwater biodiversity and improves ecological status.

Biochemical Oxygen Demand (BOD5) and total ammonium concentrations in rivers between 1992 and 2006

Note: Between 1992 and 2006, BOD5 decreased from 5 to 2 mg O2/l

Data source:

Waterbase Version 7

Downloads and more info

Concentrations of nitrate (left, NO3) and phosphorus (right, OP (orthophosphate) or TP (total phosphorus)) in European freshwater bodies in the period 1992-2005.

Note: Concentrations are expressed as annual mean concentrations for groundwater, and station weighted mean of annual mean concentrations for rivers and lakes

Data source:

Waterbase (Version 6)

Downloads and more info

Key assessment

Biochemical Oxygen Demand (BOD) and total ammonium concentration have decreased in European rivers over the period 1992 - 2005, corresponding to the general improvement in wastewater treatment. BOD and ammonium concentrations are generally highest in eastern, southern and south-eastern European rivers. The largest declines in BOD are evident in the rivers of western Europe, while the biggest drops in ammonium are apparent in eastern European countries.

Concentrations of BOD and ammonium are key indicators of the organic matter and oxygen content of water bodies. They normally increase as a result of organic pollution due to discharges from waste water treatment plants, industrial effluent and agricultural run-off. Severe organic pollution may lead to rapid de-oxygenation of river water along with increased ammonium levels and the consequent disappearance of fish and aquatic invertebrates.

The most important sources of organic waste load are household waste water, discharges from industries such as paper production or food processing and occasional silage or slurry effluents from agriculture. Increased industrial and agricultural production, coupled with a greater percentage of the population being connected to sewerage systems, initially resulted in increased discharge of organic waste into surface water across most European countries after the 1940s. Over the past 15 to 30 years, however, the biological treatment of waste water has increased and organic discharges have consequently decreased throughout Europe.

Nutrient levels in freshwaters are decreasing. The average nitrate concentration in European rivers has decreased approximately 10 % since 1998, from 2.8 to 2.5 mg N/l, reflecting the effect of measures toreduce agricultural inputs of nitrate. Nitrate levels in lakes are in general much lower than in rivers but there has also been a 15 % reduction of the average concentration in lakes.

Agriculture is the largest contributor of nitrogen pollution. Due to the EU Nitrate Directive and national measures the nitrogen pollution from agriculture has, however, been reduced in some regions during the last 10 - 15 years. European air emissions of nitrogen oxides have gone down by one-third over the last 15 years and the deposition of nitrogen on inland surface waters has also declined.

Phosphorus concentrations in European rivers and lakes generally decreased during the last 14 years, reflecting the general improvement in wastewatertreatment and reduced phosphate content of detergents over this period. In many rivers the reduction started in the 1980s. During the past few decades there has also been a gradual fall in phosphorus concentrations in many European lakes. The decrease is due to nutrient removal measures introduced by national and European legislation particularly the Urban Waste Water Treatment Directive. As treatment of urban wastewater has improved and many waste water outlets have been diverted away from lakes, point-source pollution is gradually becoming less important. Agricultura linputs of phosphorus are still significant and need increased attention to achieve a good status in lakes and rivers.

Improving groundwater quality is also important as it can be a source of nitrate in rivers thereby adversely affecting associated river systems, lakes, wetlands and dependent terrestrial ecosystems. At the European level, annual mean nitrate concentrations in groundwater have remained relatively stable since the mid-1990s following an increase during the first half of the 1990s.


EEA Core Set indicators

Data sources

More information about this indicator

See this indicator specification for more details.

Contacts and ownership

EEA Contact Info

Katarzyna Biala


EEA Management Plan

2010 1.2.2 (note: EEA internal system)


Frequency of updates

Updates are scheduled once per year in October-December (Q4)
Filed under: , ,


European Environment Agency (EEA)
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Phone: +45 3336 7100