The general status of surface water bodies is determined by the worst value of their ecological status and their chemical status (section 17 of art. 3 of RD 817/2015, of September 11).
First of all, scheduled sampling (monitoring programs) are carried out at the control points of the indicators and parameters established by RD 817/2015; the data is obtained or the corresponding indices are calculated, where appropriate, and the evaluation is carried out by natural year of the chemical and ecological status of each body of water. In the event that it is an artificial or highly modified body of water, the chemical status and ecological potential are calculated.
The chemical status is an expression of the quality of surface waters that reflects the degree of compliance with environmental quality standards (hereinafter EQS) of priority substances and other pollutants in Annex IV of RD 817/2015. The chemical state is represented by the following color code:
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Classification of the chemical state of a body of surface water |
Good |
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Good is not enough |
The ecological status is an expression of the quality of the structure and functioning of aquatic ecosystems associated with surface waters classified in accordance with RD 817/2015. The result of the ecological status is based on the combination of biological, physical-chemical and hydromorphological indicators (the hydromorphological characterization protocol is currently being applied to rivers).
For the evaluation of the ecological status, the degree of deviation of the conditions observed in the body of water is evaluated with respect to the best possible conditions, that is, the reference conditions that the body of water would present without the presence of pressures and anthropogenic impacts.
These reference conditions are established for each type of surface water body and represent the values of the hydromorphological, physicochemical and biological indicators (in accordance with Annex V of the WFD) of a very good ecological status in the bodies of surface water.
The classification of the ecological status of natural surface water bodies follows the following color coding:
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Ecological status classification of a natural surface water body |
Very good |
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Good |
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Moderate |
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Poor |
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Bad |
The classification of the ecological potential of highly modified or artificial surface water bodies follows the following color coding:
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Classification of the ecological potential of a surface water body for artificial and highly modified water bodies |
Good or better |
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Moderate |
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Poor |
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Bad |
