Selection

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This table includes additional information to the above visualized indicators, i.e. a short definition of this indicator and a description of the politically determined target values as well as explaining the political intention behind selecting this indicator.

Definition (Text from the Indicator Report 2022 - State 31.10.2022)

The indicators show the moving discharge-weighted five-year average of nitrogen concentrations in milligrams (mg) of nitrogen per litre (l) of water discharged from rivers into the North Sea and the Baltic Sea.1

1Regarding the North Sea, these are the following rivers: Eider, Elbe, Ems, Weser, Rhein, Treene, Aarlau, Bongsieler Kanal and Miele. As far as the Baltic Sea is concerned, these are the following rivers: Peene, Trave, Warnow, Langballigau, Füsinger Au, Koseler Au, Schwentine, Kossau, Goddesdorfer Au, Oldenburger Graben, Aalbeck, Schwartau, Lippingau, Hagener Au, Barthe, Duvenbaek, Hellbach, Maurine, Recknitz, Ryck, Stepenitz, Uecker, Wallensteingraben and Zarow.
Target and intention (Text from the Indicator Report 2022 - State 31.10.2022)

High concentrations of nitrogen in the seas can lead to eutrophication effects such as oxygen depletion, the loss of biodiversity and to the destruction of fish spawning grounds. Therefore, the input of nitrogen should stay below 2.8 mg nitrogen per litre discharge for the rivers flowing into the North Sea and below 2.6 mg/l for the rivers flowing into the Baltic Sea. This aligns with the management targets of the Ordinance on the Protection of Surface Waters (OGewV), which were agreed in implementation of the Water Framework Directive, as well as with those of the Marine Strategy Framework Directive and the Baltic Sea Action Plan.
Definition

The indicators represent the five-year moving average of discharge-weighted nitrogen concentrations in milligrams (mg) of nitrogen per litre (l) of water discharged from rivers into the North Sea (14.1.ab) and Baltic Sea (14.1.aa)1

1For the North Sea, these are the rivers Eider, Elbe, Ems, Weser, Rhein, Treene, Aarlau, Bongsieler Kanal and Miele. For the Baltic Sea, these are the Peene, Trave, Warnow, Langballigau, Füsinger Au, Koseler Au, Schwentine, Kossau, Goddesdorfer Au, Oldenburger Graben, Aalbeck, Schwartau, Lippingau, Hagener Au, Barthe, Duvenbaek, Hellbach, Maurine, Recknitz, Ryck, Stepenitz, Uecker, Wallensteingraben and Zarow.
Intention

High concentrations of nitrogen in the oceans can lead to eutrophication effects such as oxygen deficiency and thus to a loss of biodiversity and the destruction of fish migration areas. The management objectives of the Surface Waters Ordinance (OGewV 2016) agreed as part of the implementation of the EU Water Framework Directive (WFD 2000/60/EC) and the objectives of the EU Marine Strategy Framework Directive (MSFD 2008/56/EC) and the Baltic Sea Action Plan should apply to the input of nitrogen into the Baltic Sea and North Sea via tributaries.
Target

14.1.aa: Adherence to good quality in accordance with the Ordinance on the Protection of Surface Waters (annual averages for total nitrogen in rivers flowing into the Baltic may not exceed 2.6 milligrams per litre
14.1.ab: Adherence to good quality in acc
Type of target

14.1.aa: Consistent target every year
14.1.ab: Consistent target every year
Implemen­tation in weather symbol calculation

The nitrogen input via the inflows into the Baltic Sea (14.1.aa) should be a maximum of 2.6 milligrams per litre per year on a five-year moving average weighted by discharge and a maximum of 2.8 milligrams per litre per year via the inflows into the North Sea (14.1.ab).


Based on the target formulation, indicator 14.1.aa for 2023 is assessed as “Cloud” because the politically defined threshold value to be maintained annually was exceeded in 2023, but the average trend over the last six years points in the desired direction.


Indicator 14.1.ab is rated as “Sun” for the year 2023 because the politically defined threshold value to be maintained annually was met in 2023 and the average development over the last six years points in the desired direction.
Assessment

14.1.aa: Weathersymbol: cloud
14.1.ab: Weathersymbol: Sun
Data state

12.05.2025

Text from the Indicator Report 2022 

One of the main causes of nitrogen inputs reaching the North and Baltic Seas via inflows is nitrogen surplus in agriculture, which is measured in indicator 2.1.a. Like nitrogen, phosphorus also leads to eutrophication. Phosphorus pollution in rivers is examined separately in indicator 6.1.a.

The calculations for this indicator use monitoring data on nitrogen concentrations and on the discharge volumes of small and major rivers flowing into the North and Baltic Seas, which the German Environment Agency collates as reported by the Länder and by river basin commissions. Data is also included for smaller rivers which do not flow directly into the North or Baltic Sea but are tributaries to larger rivers. In these cases, the data for each river are taken from its last monitoring site before the confluence. The Rhine is also included in the figures, even though its estuary is not in Germany. The data for the Rhine were recorded at the point where it leaves Germany (monitoring site at Bimmen, Kleve).

The nitrogen concentrations for each river are weighted for discharge volume, so that major rivers which discharge large qualities of water have a greater influence on the average that smaller ones. To prevent the graph being distorted by single extreme events like floods or droughts, which can result in anomalously very high or very low nitrogen inputs, the values are depicted as a five-year moving average.

The average nitrogen concentration for all North and Baltic Sea inflows, weighted for discharge volume, has followed a downward trend since the beginning of the time series, with the reduction in concentration more marked for the North Sea than the Baltic. The 2016-2020 average for the North Sea inflows was a concentration of 2.8 mg/l and reached jointly the target value for the first time. For rivers flowing into the Baltic Sea, the average concentration was 3.1 mg/l for the same period and, thus, exceeded the upper limit of 2.6 mg/l.

In contrast to the aggregated indicator 14.1.a “Nitrogen inputs via the inflows into the North and Baltic Seas”, each river by itself has to meet the management target to achieve good quality, as defined by the Ordinance on the Protection of Surface Waters. The target is neither achieved for the North Sea nor the Baltic Sea.

Of the three major inflows into the Baltic Sea, the Peene, the Trave and the Warnow, only the latter had already reached the management target by 2016-2020. Nevertheless, Peene and Trave showed a small reduction in concentration across the five-year averages by 0.1 mg/l. In some of the smaller Baltic Sea inflows, concentrations of nitrogen are still several times higher than the management target, with values of up to 5.9 mg/l, and the target was only reached by a quarter of the smaller Baltic Sea inflows.

Of the North Sea inflows, only the Rhine met the management target in the period 2016 to 2020, and, hence, was mainly responsible for the joint achievement of the weighted for discharge volume target value. The five-year averages of nitrogen concentrations decreased for all major North Sea inflows (Ems, Weser, Rhein and Eider) by 0.1 to 0.2 mg/l, except for the Elbe. A slight decline was also measured by the five-year averages of nitrogen concentrations for the small North Sea inflows. Accordingly, the values were between 2.6 mg/l and 3.5 mg/l in the period from 2016-2020.