Phytoplancon is one of the 4 biological quality elements (BQE) for the assessment of the ecological status of the natural water bodies. The evaluation of this BQE is only relevant for the large rivers where the quantity of phytoplancton is significant and can be evaluated. The natural water bodies of typology VI present significant phytoplancton concentrations to allow an assessment. Some of the heavy modified waterbodies (HMWB) present significant phytoplancton concentrations too, these are the HMWB Sûre (WB III-2.2.1) and the HMWB Our (WB V-1.2). The annual frequency for phytoplancton monitoring is 6 samples between April and October.

Evaluation of the quality element “morphological conditions” per surface water body

Evaluation of the quality element “continuity” per surface water body

According to the water framework directive (Directive 2000/60/CE), the biological parameter fish are monitored in surface water bodies in order to determine the ecological status. Fish react sensitively to the continuity and the hydrological flow of surface water. Fish are therefor sampled in the SWB which have deficits here. The methodology applied for sampling is the standard NF EN 14962:2006 "water quality − guidance on the scope and selection of fish sampling methods".

According to the Water Framework Directive (Directive 2000/60/EC ), macrophytes and diatoms are monitored as two sub-elements of the aquatic flora. Macrophytes are particularly sensitive to organic pollution, trophy and hydromorphology. The diatom assemblages are different in function of concentrations of nutrients and organic pollutants.

According to the water framework directive WFD(DIR 2000/60/CE), important physico chemical parameters are measured in the surface water bodies for the assessment of the ecological status. The modalities for this monitoring are stated in the grand ducal Regulation of 30 December 2010 (règlement grand-ducal you 30 décembre 2010 concernant l 'évaluation of the dimension d' eau de surface).

Overall evaluation of the hydromorphological status per surface water body. The assessment of the hydromorphological status is based on the mapping and the assessment of the structural quality of the Luxembourgish watercourses. The quality element “morphology” has not been covered in the framework of the structural quality mapping, but only the two quality elements related to continuity and morphology. The hydromorphological status is assessed in 5 classes.

The macroinvertebrates are sampled according to the French method IBGN ( indice biologique global normalisé , agences de l' eau 2000). The results allow to classify the surface water bodies into 5 classes : high - good - moderate - poor - bad. Macroinvertebrates are sensitive to the hydromorphology, organic pollution , biological continuity , water regime and acidification. The Macroinvertebrates are one out of four biological parameters of the ecological status of surface water.