A too high concentration of blue-green algae was found in the large Rietplas-Rietstrand. Earlier a warning was given for Large Rietplas-Watersportstrand, Kleine Rietplas and Large Rietplas-Parelstrand. The warning is still in force in these places.
The province has placed warning signs at the Rietstrand. Blue algae can cause various physical complaints, such as headache and stomach or intestinal complaints.