The "good ecological potential" is the environmental quality objective defined by the water framework directive for artificial and heavily modified surface water bodies. The assessment of the ecological potential is presented in four classes ranging from 1 to 4 (good and higher, moderate, poor, bad). The classification of the ecological potential is based on the biological, physico-chemical and in some cases also the hydromorphological quality elements.

The ecological status of the natural surface water bodies 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, physico-chemical quality elements and in some cases also the hydromorphological quality elements.