Inspectors regularly check the quality of Dutch natural water at more than 900 swimming locations between 1 May and 1 October. When a warning or swim advice is issued, it is automatically added to the map. This way you are always aware of the bathing water quality in your area.
In natural water it is especially important to watch out for blue-green algae, Rijkswaterstaat warns. Blue-green algae can sometimes be seen as a green or blue layer on the water surface. Sometimes it is also in the water without being visible. Contact with blue-green algae can cause skin irritations, but also headaches and intestinal and stomach problems.
Waterschap Rivierenland, among others, advises people not to swim in ditches and canals in the regions Rijk van Nijmegen, the Land van Maas en Waal, the Bommelerwaard and the Land van Heusden and Altena because of blue-green algae. This is because blue-green algae has been found in the Meuse.