Luxembourg's Administration de la gestion de l'eau has finally confirmed the lifting of the alert relating to the efflorescence of cyanobacteria in the Upper-Sûre lake that was originally put in place during August this year.
An abrormally high concentration of blue algae blooms was detected in the water of the Esch-sur-Sure reservoir in the north of the Grand Duchy during August, and regular analyses were conducted by the Luxembourg Institute of Science and Technology (LIST) that revealed sometimes extraordinarily high toxin levels in the water of the lake and biomass at recreation areas.
The situation has now clearly improved. The seasonal changes at both climatological and hydrodynamics levels of the Upper Sûre lake have resulted in a significant decline in the biomass of cyanobacteria and the dissipation of efflorescences. This new development thus brings to an end the alert to the microbiological and toxic risks in the public health related to the direct contact with the efflorescence of cyanobacteria.
The practice of recreational activities and sports, especially diving, can therefore resume. However, in accordance with the provisions of the Grand-Ducal Regulation of 19 May 2009, the bathing season remains from 1 May to 31 August in defined bathing sites and bathing is prohibited outside Of this season.
The observation of cyanobacteria and the analysis of their toxins will be continued in the coming weeks.
With respect to fish consumption, the Food Security Division of the Ministry of Health recommends that fish from this water should not be consumed during periods of cyanobacterial bloom. However, it can not exclude the bioaccumulation effect of toxins produced in the liver of fish.
