Archive photo shows the Weiswampach lake during a triathlon Delano/archives

Archive photo shows the Weiswampach lake during a triathlon Delano/archives

According to a press release issued on Tuesday, Liser researchers found concentrations of microcystin which were over twice the alert threshold.

Blue-green algae or cyanobacteria grows in ponds and lakes where waters are calm and temperatures are high. The type of cyanobacteria found in this lake produces toxins, which can be harmful to human and animal health.

The authority imposed an immediate ban on Tuesday on swimming, allowing dogs to bathe in or drink water from the lake and on eating fish caught in the lake.

On 27 August, the authority banned bathing at the Rommwiss beach of the Upper Sûre lake. Swimming remains authorized at the rest of the lake.

Meanwhile, no cyanobacteria has been identified at the Remerschen lakes in the east of Luxembourg. As a result swimming remains authorized.

To monitor the situation, visit www.waasser.lu