2.2 Surface waters: Status and pressures

2.2.1        Ecological status

Ecological status or potential is an assessment of the quality of the structure and functioning of surface water ecosystems. It shows the influence of all pressures, like pollution, habitat degradation, hydrological changes and others in rivers, lakes, transitional waters and coastal waters. Ecological status is based on biological quality elements and supporting physico-chemical and hydromorphological quality elements.

On a European scale, around 44 % of the surface water bodies are in good or high ecological status or potential, with lakes and coastal waters having better status than rivers and transitional waters[1]. There has been limited change in ecological status since the first RBMPs were reported, although this comparison is difficult to make since the data underpinning the 1st RBMPs was of much lower quality than the data for the 2nd RBMPs. The status of many individual quality elements that make up ecological status is generally better than the ecological status as a whole. The analysis shows that the ecological status of some biological quality elements has improved from the first to the second RBMPs.

[1] Compared to the results in EEA (2018) there is an increase in the proportion of surface water bodies with high or good ecological status (from 40 % to 44 %) due to better than average ecological status in the extra included countries (Greece, Ireland, Lithuania and Norway). See also https://tableau.discomap.eea.europa.eu/t/Wateronline/views/WISE_SOW_SWB_Status_Compare/SWB_EcologicalStatus_Category?:embed=y&:isGuestRedirectFromVizportal=y&:display_count=n&:showAppBanner=false&:origin=viz_share_link&:showVizHome=n

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2.2.2        Chemical status

For surface waters, good chemical status is defined by limits (environmental quality standards (EQS)) on the concentration of certain pollutants found across the EU, known as priority substances. In the second RBMPs, 31 % of surface water bodies are in good chemical status, while 35 % have not achieved good chemical status and for 34 % their status is unknown[2].

In many Member States, relatively few substances are responsible for failure to achieve good chemical status. Mercury causes failure in a large number of water bodies. If the widespread pollution by ubiquitous priority substances, including mercury, is omitted, the proportion of water bodies in good chemical status increases to 64 %, with 3 % that have not achieved good status and 34 % whose status is unknown[3]. The main reasons for failure to achieve good status are atmospheric deposition and insufficiently treated discharges from waste water treatment plants.

Since the publication of the first RBMPs, Member States have made progress in tackling priority substances, leading to a reduction in the number of water bodies failing to meet standards for substances such as priority metals (cadmium, lead and nickel) and pesticides.

[2] Compared to the results in EEA (2018) there is a marked increase in the proportion of surface water bodies with unknown chemical status (from 16 % to 34 %) due to nearly all surface water bodies in Norway and Ireland having unknown chemical status. The high proportion of unknown status reduces the percentage in good or failing to achieve good chemical status. See also https://tableau.discomap.eea.europa.eu/t/Wateronline/views/WISE_SOW_SWB_SWPrioritySubstanceWithoutUPBT/Category?:embed=y&:display_count=n&:showAppBanner=false&:showVizHome=n&:origin=viz_share_link

[3] The high proportion unknown status also reduces the proportion in good chemical status from 81 % to 64 %.

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2.2.3        Pressures on surface waters

The main significant pressures on surface water bodies are hydromorphological pressures (affecting 34 % of water bodies), diffuse sources (33 %), particularly from agriculture and atmospheric deposition, particularly of mercury (31 %), followed by point sources (15 %) and water abstraction (6 %)[4]. The main impacts on surface water bodies are nutrient enrichment, chemical pollution and altered habitats due to morphological changes.

[4] Compared to the results in EEA (2018) there is a decrease in the proportion of surface water bodies affected by the listed pressures (between 3 to 7 percentage points), because of better status and less pressures in the extra included countries (Greece, Ireland, Lithuania and Norway). See also https://tableau.discomap.eea.europa.eu/t/Wateronline/views/WISE_SOW_PressuresImpacts/SWB_Pressures?:embed=y&:showAppBanner=false&:showShareOptions=true&:display_count=no&:showVizHome=no

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