The ecological status of the natural waterbodies is assessed in 5 classes going from 1 to 5 (high, good, moderate, poor, bad). The classification of the ecological status is based on the biological quality elements and the physico-chemical quality elements and in some cases also the hydromorphological quality elements.

The global status of a surface water body is determined by its ecological and chemical status.

Overall evaluation of the hydromorphological status per surface water body. It is a “pessimistic assessment” because only the worst of the two parameters morphology an continuity is retained. The hydromorphological status is assessed in 5 classes.

The chemical status of the water bodies is assessed as being good or failing to achieve good chemical surface. The definition of good chemical status is based on the annex X of the water framework directive which contains a list of priority substances and environmental quality standards (EQS) for each of these substances. This list is regularly updated in compliance with the directive 2008/105/EC and its revisions.